PB 11.5.1

I am trying to compile a .NET assembly target containing a single user
object. When I try to Deploy I get this error:

Error when generating PBD files.

The DeployLog.txt file is empty, so I have no idea about the cause of
the error.
Since this is my first non-trivial assembly, I am sure making something
wrong... I read the "Deploying Applications and Components to .NET"
manual but found no answer.

Any suggestions?

Thank you,