Fink cannot be installed on this computer (Fink on Mac Mini)

I try to install Fink 0.8.1 for OS X 10.4 PPC on my MacMini, which runs on OS X 10.4.

Strangely, when I run the dmg the installation routine gives me the message "Fink cannot be installed on this computer. This installer is for OS X 10.4 only. Please visit ..."

Anyone experienced similar problem? Any idea what's wrong?

Thanks.
Mathias