hmm that seems to be strange
the problem is i cannot help you anymore cause as i said before nimbuzz is forbidden in my country
maybe it doesn't work with icq or maybe it works if your contacts has nimbuzz

well you can try doing a lot of things to manage it to work
but what i know is that it worked with my msn/jabber account also skype/jabber (when nimbuzz used to have a skype service but they deleted it now)

that's all what i can say