Help!!! 003 rack not detected by i Mac!

[joshua12]

This is my iMac spec -

Machine Name: Mac
Machine Model: iMac7,1
Processor Name: Intel Core 2 Duo
Processor Speed: 2.4 GHz
Number Of Processors: 1
Total Number Of Cores: 2
L2 Cache (per processor): 4 MB
Memory: 1 GB

mac os : 10.4.8

I already download os from 10.4.10 to 10.4.8, but iMac does not detect oo3. I have protools le 7.3(003 rack).
After I install protools and run the program, it shows messages that ' unable to locate digidesign hardware...'.
Firewire cable is ok, and the port on the back of imac is no problem. But When I connect 003 to my windows system computer, it works.
I do not understand why iMac can not detect 003.
iMac is totally new. Never installed any other program except protools.
I download prebind_script and once run it. It shows the message that there is no problem.

What shoud I do?