Motion 2.1.2 can't install

I see that Motion 2.1.2 update is available, in my Software Update browser, and it says I should install it but having downloaded it I am now told that Motion cannot be installed on this machine. I have version 2.1.
This is a PPC DP2 Ghz G5 with 2.5 Gigs RAM, running 10.4.6
Anyone know what is going on?



Post Edited (07-02-06 10:02)