HRESULT: 0x80131515 on Release

We use a third party Dll, called EASendMail40.dll, the thing is that when I build the solution on debug mode everything goes perfect, but when release mode it throws 2 errors Hresult: 0x80131515 for two of the projects.

I've being looking for an answer and anything works.

Things I've already tried:

• Unlock File (file was never locked)
• Copy the file locally
• Un-reference and reference again to both of the projects.
• Add the "LoadFromRemoteSources" tag on the .config.

Additional info:

The error shows an incorrect path to the file, but the .CSProj is correct.

I use the same DLL on another project in the same solution and I have no problems with it.

The solution builds perfect on a workstation, debug and release mode, the problem is when building on the server.