Please retry installation

since last update of dev tools, i don’t see anymore RubyCocoa
Application in XCode :

File > New Project … > Assistant > Application

i’ve tried to re-install RubyCocoa using
“RubyCocoa-0.12.0-OSX10.4universal.dmg” on my iMac G5 (ppc) BUT, this
ends up with :

please retry installation (errors occured during installation).

did someone else get this kind of prob ???