Because password for that pool is rigname.password
It is a little different than most pools, however, your Rig Name is 2, and your PW is 123, thus in the miner the password should be "2.123"
Hope this helps!!
thanks for your answer

I'm not quite sure if I understand you right...
do you mean like this:
-u Rasopo531.2 -p 2.123
I just tried it and it didnt change anything...

and also... for the cudminer I use the same settings (indcluding the pw) but with different worker... and there it works... it's only the cgminer on ati...
thanks...