LNK2019 FSynthSlateStyleSet::Get error on my own class?

Hello everyone,

I have one unresolved external error.

1>MySynth2DSlider.cpp.obj : error LNK2019: unresolved external symbol “public: static class TSharedPtr __cdecl FSynthSlateStyleSet::Get(void)” (?Get@FSynthSlateStyleSet@@SA?AV?$TSharedPtr@VFSlateStyleSet@@$0A@@@XZ) referenced in function “public: __cdecl SSynth2DSlider::FArguments::FArguments(void)” (??0FArguments@SSynth2DSlider@@QEAA@XZ)
1>F:\Test\Binaries\Win64\UE4Editor-Test.dll : fatal error LNK1120: 1 unresolved externals

RebuildWidget() function is overridden and in use by UMySynth2DSlider

added Synthesis modules to Bulid.cs, but the problem still occurs.