I don?t get a confirmation window for booked appointments. Why?

Hi there,

I just installed AP+ and its really nice. I have some issues with the booking system. People who book an appointment don´t get a feedback in the webinterface. If you click on the confirmation button, the loading wheel seems to turn all the time. Who can I solve the problem?

Here is the website:

http://www.inst.uni-giessen.de/career-centre/individuelle-karriereberatung/