.NET com class library to vb6

Question

hi there,

i have created and registered a com class library following the instractions of this article:
http://www.c-sharpcorner.com/uploadfile/yougerthen/how-to-create-a-com-object-using-vs-2008-and-consume-it-from-vb-6-0-client-application-part-ii/
i have also created a vb6 project and reference the com library. i built and run the project and it worked fine.
A few days later i run the exe built the first time and i got the following error:
Run-time error '-2147467261 (80004003)':
Object reference not se to an instance of an object.
the period between the first built and the second run i haven't unregistered or registered the library again and i haven't changed or built the project.
the register command i used was:
C:\WINDOWS\Microsoft.NET\Framework\v2.0.50727>regasm /codepage myLib.dll /tlb:myLib.tlb
any ideas?

thanks in advance