Airplay Spotify wont start playing music on my htpc

[cdavve]

Hey Guys, really hope someone can help me with this.

Im using an Ipad2 and a HTPC with XBMC and would like to airplay my spotify to it. It work with youtube and other programs but not with spotify. I activate the Airplay and the track gets paused and nothing gets played on XBMC.

I got Itunes installed on the HTPC runs on XP, newest IOS on the Ipad and good wifi connection. 

Thankful for help, Cheers!