No engine version assigned to project

my project doesnt recognizes my engine version anymore.
while i changed to version 4.12, people submitted 4.11 files via perforce.
now as you can see on the picture the version is not displayed anymore.

when i try to package he tells me

UnrealBuildTool: ERROR: Unable to determine module type for D:\xxx\Projectname\Projectname.Build.cs
MainFrameActions: Packaging (Windows (64-bit)): CommandUtils.Run: Run: Took 3,2196523s to run UnrealBuildTool.exe, ExitCode=5

anyone knows how to solve that?

thanks in advance