Rating question

I have won 2 games against a p1200 opponent and my rating go down... How is it possible?

While you have provisional status (first 20 rated games) your rating is recalculated every game according to a different set of rules, and weird things are possible - more so if you're both provisional. For example, if your early wins were against strong players and your later wins were against much weaker players, your overall margin average could go down. Don't worry about it, things make much more sense once you pass the 20 mark.

Thank you