Problem mounting Hard Drive

I bought an IBM Travelstar 40G HD expecting to upgrade my Mac G3 PowerBook Firewire model. I put the new HD in an external Firewire case and connected it to my existing system. Everything is fine. I copied my files over to the new HD in the ext case.

Now – I moved the new HD into the HD bay of my PowerBook and the original internal HD into the External case. System comes up OK, but the new 40G HD (now sitting in the internal PB bay) doesn’t mount.

Disk First Aid and Norton Utilites don’t see it.

Is there a trick to mounting this new HD?

thanks

-td