ports opening for aMule

Hi all.
I have been reading all posts but no solution found for opening ports when using aMule. I have a PC which works fine and gets high Id when connecting to eMule. I have installed aMule for mac and when launching this app. a message appears telling me that port "xx", or any other has no chance to get opened :"port #x not available", no matter which port I try with. I mean: PC works fine with the same router than Mac does not.

Thanks in advance. (I am a rookie in Mac).

P.S: I forgot mentioning that firewall (Mac) was yet disabled.

Message was edited by: anseso