Unfortnately the customized hildon-desktop of mohammadAG needs a pin procedure ... ie a procedure that stop the reinstallation of the default packages by the repo ...
But for some strange reasons i don't know why in some n900 the pin procedures has no problems and in others it gives that error...
By the way, maybe i've understood the problem.... tonight i'll release a new version of maemodder with the correct dependencies and with the solution for this bug .. i hope.. :/