I've installed 4.3 - 5.0 - 5.1
I think I didn't meet same error before.
BTW, in CodeLab 5.1, after insert PanSliderControl, following code is generated.
PanSliderControl Amount4 = Pair.Create(0); // Slider 3 Description
As you know, that code should be fixed to following:
PanSliderControl Amount4 = Pair.Create(0.000, 0.000); // Slider 3 Description
And, after fixing it, that code works!