Kivy/Raspi着色器異常

我正在使用Kivy在Raspi 3上編寫一個圖形用戶界面，並且它一直在工作得很好，但現在我添加了幾個「屏幕」，在返回到前一個屏幕時崩潰。Kivy/Raspi着色器異常

基本上來自模仿我希望能夠去其他三個屏幕（TCS，EPC，CT）中的任何一個，並且能夠返回到Mimic。我可以去模仿和隨後對所有這些屏幕，但點擊返回按鈕，出現以下消息導致程序崩潰：

Traceback (most recent call last): 
    File "GUI.py", line 1329, in <module> 
    MainApp().run() 
    File "/usr/local/lib/python2.7/dist-packages/kivy/app.py", line 828, in run 
    runTouchApp() 
    File "/usr/local/lib/python2.7/dist-packages/kivy/base.py", line 500, in runTouchApp 
    EventLoop.window.mainloop() 
    File "/usr/local/lib/python2.7/dist-packages/kivy/core/window/window_egl_rpi.py", line 90, in mainloop 
    self._mainloop() 
    File "/usr/local/lib/python2.7/dist-packages/kivy/core/window/window_egl_rpi.py", line 85, in _mainloop 
    EventLoop.idle() 
    File "/usr/local/lib/python2.7/dist-packages/kivy/base.py", line 339, in idle 
    self.dispatch_input() 
    File "/usr/local/lib/python2.7/dist-packages/kivy/base.py", line 324, in dispatch_input 
    post_dispatch_input(*pop(0)) 
    File "/usr/local/lib/python2.7/dist-packages/kivy/base.py", line 290, in post_dispatch_input 
    wid.dispatch('on_touch_up', me) 
    File "kivy/_event.pyx", line 718, in kivy._event.EventDispatcher.dispatch (kivy/_event.c:8191) 
    File "/usr/local/lib/python2.7/dist-packages/kivy/uix/behaviors/button.py", line 179, in on_touch_up 
    self.dispatch('on_release') 
    File "kivy/_event.pyx", line 714, in kivy._event.EventDispatcher.dispatch (kivy/_event.c:8146) 
    File "kivy/_event.pyx", line 1225, in kivy._event.EventObservers.dispatch (kivy/_event.c:14035) 
    File "kivy/_event.pyx", line 1109, in kivy._event.EventObservers._dispatch (kivy/_event.c:12816) 
    File "/usr/local/lib/python2.7/dist-packages/kivy/lang/builder.py", line 64, in custom_callback 
    exec(__kvlang__.co_value, idmap) 
    File "<string>", line 540, in <module> 
    File "kivy/properties.pyx", line 423, in kivy.properties.Property.__set__ (kivy/properties.c:5572) 
    File "kivy/properties.pyx", line 461, in kivy.properties.Property.set (kivy/properties.c:6405) 
    File "kivy/properties.pyx", line 516, in kivy.properties.Property.dispatch (kivy/properties.c:7105) 
    File "kivy/_event.pyx", line 1225, in kivy._event.EventObservers.dispatch (kivy/_event.c:14035) 
    File "kivy/_event.pyx", line 1131, in kivy._event.EventObservers._dispatch (kivy/_event.c:13193) 
    File "/usr/local/lib/python2.7/dist-packages/kivy/uix/screenmanager.py", line 973, in on_current 
    self.transition.start(self) 
    File "/usr/local/lib/python2.7/dist-packages/kivy/uix/screenmanager.py", line 369, in start 
    self.add_screen(self.screen_in) 
    File "/usr/local/lib/python2.7/dist-packages/kivy/uix/screenmanager.py", line 505, in add_screen 
    self.fbo_out = self.make_screen_fbo(self.screen_out) 
    File "/usr/local/lib/python2.7/dist-packages/kivy/uix/screenmanager.py", line 469, in make_screen_fbo 
    fbo = Fbo(size=screen.size) 
    File "kivy/graphics/fbo.pyx", line 150, in kivy.graphics.fbo.Fbo.__init__ (kivy/graphics/fbo.c:3155) 
    File "kivy/graphics/instructions.pyx", line 754, in kivy.graphics.instructions.RenderContext.__init__ (kivy/graphics/instructions.c:11094) 
    File "kivy/graphics/shader.pyx", line 186, in kivy.graphics.shader.Shader.__init__ (kivy/graphics/shader.c:4152) 
    File "kivy/graphics/shader.pyx", line 695, in kivy.graphics.shader.Shader.vs.__set__ (kivy/graphics/shader.c:11550) 
    File "kivy/graphics/shader.pyx", line 557, in kivy.graphics.shader.Shader.build_vertex (kivy/graphics/shader.c:9283) 
    File "kivy/graphics/shader.pyx", line 587, in kivy.graphics.shader.Shader.link_program (kivy/graphics/shader.c:9736) 
Exception: Shader didnt link, check info log.

全部代碼是在這裏：https://github.com/ISS-Mimic/Mimic/blob/master/Pi/GUI.py

相關的（我認爲）片段：

class MainApp(App): 

    def build(self): 
     self.mimic_screen = MimicScreen(name = 'mimic') 
     self.fakeorbit_screen = FakeOrbitScreen(name = 'fakeorbit') 
     self.eps_screen = EPS_Screen(name = 'eps') 
     self.ct_screen = CT_Screen(name = 'ct') 
     self.tcs_screen = TCS_Screen(name = 'tcs') 

     root = MainScreenManager(transition=WipeTransition()) 
     root.add_widget(MainScreen(name = 'main')) 
     root.add_widget(CalibrateScreen(name = 'calibrate')) 
     root.add_widget(self.mimic_screen) 
     root.add_widget(self.fakeorbit_screen) 
     root.add_widget(self.eps_screen) 
     root.add_widget(self.ct_screen) 
     root.add_widget(self.tcs_screen) 
     root.add_widget(ManualControlScreen(name = 'manualcontrol')) 
     root.current= 'main' 

     Clock.schedule_interval(self.update_labels, 1) 
     Clock.schedule_interval(self.checkAOSlong, 5) 
     return root

和KV代碼：

Builder.load_string(''' 
#:kivy 1.8 
#:import kivy kivy 
#:import win kivy.core.window 
ScreenManager: 
    MainScreen: 
    FakeOrbitScreen: 
    EPS_Screen: 
    CT_Screen: 
    TCS_Screen: 
    ManualControlScreen: 
    MimicScreen: 
    CalibrateScreen: 
<MainScreen>: 
    name: 'main' 
    FloatLayout: 
     orientation: 'vertical' 
     Image: 
      source: './imgs/iss.png' 
      allow_stretch: True 
      keep_ratio: True 
     Button: 
      size_hint: 0.3,0.1 
      pos_hint: {"center_x": 0.2, "center_y": 0.9} 
      text: 'Fake Orbit' 
      font_size: 30 
      width: 50 
      height: 20 
      on_release: root.manager.current = 'fakeorbit' 
     BoxLayout: 
      size_hint_y: None 
      Button: 
       text: 'Control' 
       font_size: 30 
       width: 50 
       height: 20 
       on_press: root.changeManualControlBoolean(True) 
       on_release: root.manager.current = 'manualcontrol' 
      Button: 
       text: 'Calibrate' 
       font_size: 30 
       width: 50 
       height: 20 
       on_release: root.manager.current = 'calibrate' 
       on_release: my_button.disabled = False 
      MyButton: 
       id: my_button 
       text: 'Mimic' 
       disabled: True 
       font_size: 30 
       width: 50 
       height: 20 
       on_release: app.root.current = 'mimic' 
      Button: 
       text: 'Exit' 
       font_size: 30 
       width: 50 
       height: 20 
       on_release: app.stop(*args) 
<FakeOrbitScreen>: 
    name: 'fakeorbit' 
    ...   
<ManualControlScreen>: 
    name: 'manualcontrol' 
    ... 
<CalibrateScreen>: 
    name: 'calibrate' 
    ... 
<CT_Screen>: 
    name: 'ct' 
    FloatLayout: 
     Image: 
      source: './imgs/iss2.png' 
      allow_stretch: True 
      keep_ratio: False 
     Button: 
      size_hint: 0.3,0.1 
      pos_hint: {"Left": 1, "Bottom": 1} 
      text: 'Return' 
      font_size: 30 
      on_release: app.root.current = 'mimic' 
<TCS_Screen>: 
    name: 'tcs' 
    FloatLayout: 
     Image: 
      source: './imgs/iss2.png' 
      allow_stretch: True 
      keep_ratio: False 
     Button: 
      size_hint: 0.3,0.1 
      pos_hint: {"Left": 1, "Bottom": 1} 
      text: 'Return' 
      font_size: 30 
      on_release: app.root.current = 'mimic' 
<EPS_Screen>: 
    name: 'eps' 
    FloatLayout: 
     Image: 
      source: './imgs/iss2.png' 
      allow_stretch: True 
      keep_ratio: False 
     Button: 
      size_hint: 0.3,0.1 
      pos_hint: {"Left": 1, "Bottom": 1} 
      text: 'Return' 
      font_size: 30 
      on_release: app.root.current = 'mimic' 
<MimicScreen>: 
    name: 'mimic' 
    FloatLayout: 
     id: mimicscreenlayout 
     Image: 
      source: './imgs/iss2.png' 
      allow_stretch: True 
      keep_ratio: False 
     Button: 
      size_hint: 0.3,0.1 
      pos_hint: {"center_x": 0.65, "center_y": 0.65} 
      text: 'EPS' 
      font_size: 30 
      on_release: root.manager.current = 'eps' 
     Button: 
      size_hint: 0.3,0.1 
      pos_hint: {"center_x": 0.65, "center_y": 0.5} 
      text: 'CT' 
      font_size: 30 
      on_release: root.manager.current = 'ct' 
     Button: 
      size_hint: 0.3,0.1 
      pos_hint: {"center_x": 0.65, "center_y": 0.35} 
      text: 'TCS' 
      font_size: 30 
      on_release: root.manager.current = 'tcs' 
     Button: 
      size_hint: 0.3,0.1 
      pos_hint: {"Left": 1, "Bottom": 1} 
      text: 'Return' 
      font_size: 30 
      on_release: root.changeMimicBoolean(False) 
      on_release: root.changeSwitchBoolean(False) 
      on_release: app.root.current = 'main' 

''')

從GUI參考圖片：每個屏幕的作品，除了在從EPS返回精細，TCS，或CT（返回返回到主從模仿正常工作）