impossible to include header file of widgetcomponent

You can ignore that. It’s just intellisense not catching up. I know its annoying but there is nothing you can do about.

i want to include ‘Components/WidgetComponent.h’ like this

and vs2015 has error message.
however,i have tried lots of method but cannot include it.

the build.cs file:

the project.h file:

the most strange thing is that the project can be successfully compiled even exists the error message!
it really influence writing program。
the problem has confused me a few days. i am eager for any help!