When i joined this site, it was possible to get 50$ no deposit bonus on pokerstars if you passed the quiz, which i did...

But now when i want to exchange it, i can only do it on PartyPoker, Poker770, Betfair, Everest Poker, Titan Poker.

is there still a way i can exchange it to Pokerstars (since i'm only intrested in that site, and that also the reason is why i signed up here.)

thanks for your help