incorrect Painter serial number

I have a Painter 4.0 cd which I have been trying to install in my imac (DV, graphite) which is booted in OS 9.2. The software was an upgrade from Painter 2.0. When I purchased it, the company gave me a serial number for it; as they said the old Painter 2.0 serial number would not work with it. I had installed it in an earlier mac (Performa 5200) with no problem. It installs fine on the iimac, but when I try to open it, I get a message that I have entered an "incorrect Painter serial number". This is the exact serial number that comes up on the "About Painter" screen on the old computer; also I have it written down in two places, so I'm sure this is the right one. (I also have the old one from Painter 2.0, which doesn't work either). I have the program saved on an external hard drive and have just copied it to the imac, but some of the features aren't working, which is why I wanted to do a new install.
I contacted Corel, but they don't have any information on the old Fractal software.
Any ideas?
Thanks.