I have Transmission 1.54 on my Powerbook G4 1.33 GHz with Mac OS X 10.4.11 Tiger. (Yes, I know the system is outdated.)

I am using a wireless router to connect to the internet at home. I configured my Powerbook to have a static IP, and I forwarded a port (for both UDP and TCP) from the router firewall to the IP of my Powerbook. The port is show as OPEN in Transmission preferences.
However, I cannot connect to any tracker. The info button on Transmission showed that there were no responses from the trackers.
Strangely, I have a MacBook with Mac OS X Leopard with an up-to-date version of Transmission. (I forgot the version and I am not at home now.) My MacBook has also a static IP with a port forwarded for Transmission. And it has no problem at all connecting to the same trackers that I tried on my Powerbook.
I even tried other bittorrent clients on my Powerbook G4 (Bits on Wheels, Tomato, etc). It's the same issue: No response from the trackers.
Does anyone have the same problem on Mac OS X 10.4.11? Any solutions?
Thanks a lot!