I have create a database connection dll successfully, registered the dll and it works well on using it with my vb6 application.
Now here comes I have to update that dll, overwrite the old dll and register the dll again and use it on my project.
However, it seems that the application cannot recognize that I have to remove the old dll from the reference and replace with the new dll and recompile it.
Sounds like a common problem. I suggest you read some of the many resources on the subject, several located within the VB6 manual you should have read thoroughly. Here are just a few: