"No such device or address" error message

I have written a linux pci device driver. It's finding the hardware, talking to it ok (I know this as I have printk statements throughout). However, when I try to open it from a test program i get an error with the message "No such device or address". It looks like the open function is not even getting called.

I have checked the driver is present in the right places (/dev/driver0 exists) and I'm stuck as to why I continually get this message. I have written drivers for 2.4 kernels and they work fine, in fact this is the first driver I have tried to write for a 2.6 kernel.

Any obvious things I might have missed out?

[DriverDemet]

Did you ever get this resolved? I am having the same problem.