The custom UFL not show in CR Additional Function List, some project show.

I have the same problem as Mr. Chaiwat Trakanratsanti in its issue of April 9 , 2015. Here is his text:

"After study 1525014 - Sample C # .NET UFL and Localization Formula function That recommend by Don Williams I follow the CRUFL_CS_ExchangeRate sample project The project build with Register for COM Interop option and add to GAC It's success to show in CR Additional Function . . . . list. Later I created a new project for my purpose . It success to show in CR Additional Function List . Aim it 's modified . Then I created new one . It fails to show in the list . My new DLL is 12 letters long CRUFL starting with prefix . My class is ComVisible and : has a Guid and implements an interface. My functions are public and return a String . I have registered DLL through Visual Studio build option and gacutil . What else am I missing ? "

Unfortunately, you did not answer .

Are there a solution?

Thanks a lot for your help.

My setup : Visual Studio 2013

Windows 8.1 64-bit