Leopard Installation disk does not recognize version 10.4.1

I have a problem installing Leopard. I successfully installed the program on my iBook G4, but when i tried to install on the mac mini (1.66 GHZ, core duo) i got the message that it could not find version 10.4 on my mac. i am certain it is there, as I checked "about this mac". Furthermore, when I attempted to reinstall OS Tiger, just in case, the mac mini failed to recognize that disk as well (i forgot the exact message it gave me). I have already run disc utility to check for any repairs, and none were needed.

Any help appreciated.

Already upgraded to 10.4.1.1

Thank you
I forgot to mention that I had done that, and still got the same result.