>What are some reasons why an OCX can't be registered on a PC?
>
>I have a client running Win98 and they can't register a third party OCX on their PC. Our setup.exe has successfully installed and registered this OCX on hundreds on PCs. However, this client can't get the OCX registered.
>
>When they run our app, they get an OLE error. When they try to manually register the OCX, they get an error.
>
>What kind of things cause this to happen.
>

WHat error do you get when trying to register?

Some ocxs have dependencies- check the documentations for the control to see what other dlls might need to be distributed. If the documentation does not state, you can use the depends.exe tool that comes with VS to determine what other files are needed.