PlacementModeModule.h to be first header included and it is...why the error?

Development Programming & Scripting
1

Trying to understand the source of this error. I open up the cpp and it is the first header included.

E:\UnrealEngineSource\Engine\Source\Editor\PlacementMode\Private\PlacementModeModule.cpp(1): error : Expected PlacementModeModule.h to be first header included.

2

Deleted the the intermediate, binary folders, etc; generated project files and this error message went away.