EditBox has ShowOnScreenKeyboardFor Error

I do not know or want to activate the onscreenkeyboard, but if I use TextBox it has an exception.
How do I get rid of it

Exception System.NullReferenceException - CLR_E_NULL_REFERENCE (1)

#### Message: 
#### GHIElectronics.TinyCLR.UI.OnScreenKeyboard::.ctor [IP: 0045] ####
#### GHIElectronics.TinyCLR.UI.Application::ShowOnScreenKeyboardFor [IP: 000c] ####
#### GHIElectronics.TinyCLR.UI.Controls.TextBox::OnTouchUp [IP: 0014] ####
#### GHIElectronics.TinyCLR.UI.RoutedEventArgs::InvokeHandler [IP: 0029] ####
#### GHIElectronics.TinyCLR.UI.EventRoute::InvokeHandlers [IP: 00a3] ####
#### GHIElectronics.TinyCLR.UI.UIElement::RaiseEvent [IP: 0052] ####
#### GHIElectronics.TinyCLR.UI.Input.InputManager::ProcessStagingArea [IP: 009b] ####
#### GHIElectronics.TinyCLR.UI.Threading.Dispatcher::PushFrameImpl [IP: 0054] ####
#### GHIElectronics.TinyCLR.UI.Threading.Dispatcher::PushFrame [IP: 0018] ####