I have a class file my imports statement only working in debug mode when changed to release mode giving error

I have the following : which is only working in debug mode. the moment i change it is showing as redline this imports statement.

Imports POP3Client

project name is Emailbot05
in release mode i changed to 

Imports Emailbot05.POP3Client
it recognized, but saying not defined as public 
how should i declare as public.

Thanks a lot for the helpful info.