yui dialog=> charset problem

[ragtek]

hi
i'm using a yui dialog for my messengersystem http://www.ragtek.org/videos/pmnewpopup.htm

here i have a problem
my site have

Code:
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yui is sending the data with utf-8 and i have no idee where i can change this, so all my special caracters öäü are not working they are send as: #ä+üpö