let me tell you that before ask a new question I read the other question based on same subject. I understand few things, but I guess I missing the main point.
I create a very simple dll via Visual Studio I tried in C# and in VB but same results.
This class is very simple it return a String with "Hello World"
When I compiled with no error I go in the folder I take the file.dll I copy in another folder an I open Excel VBA and in the Reference I try to add that library as dll and there I got the first error, so I thought that I have first to register so I tried via regsvr32, using regasm in both cases I got back error, using regsvr32 I got back the error that is in the topic of this post.
So basically let say as other experts replyed that maybe the dll is not meant to be registerd, anyone can then explain me how can I use it in Excel VBA?