How to derive from VerticalBox?

I tried to add new c++ class derived from VerticalBox but after adding class this message showed up:

"Successfully added class ‘MyVerticalBox’, however you must recompile the ‘Puzzle1’ module before it will appear in the Content Browser. Failed to automatically hot reload the ‘Puzzle1’ module.

Would you like to open the Output Log to see more details?"

Now I can’t compile because I have lot’s of errors in engine files, for example:

“Error C:\Program Files\Epic Games\UE_4.14\Engine\Source\Runtime\UMG\Public\Components/Widget.h(135) : error C2059: syntax error: ‘)’”

Am I doing something wrong? Or how to fix it? Please give me detailed answer, I am new to UE and C++.