Why cant I change sounds for alerts in Mavricks

Hi there,

I tried changing sound affects in System Preferences/Sounds/Sounds Effects, and then selecting the one I want, but it's not playing at all now. Before that I had another sound for the alert. I'd like to change it for when I hear the notifications comming from my iCal I don't enjoy that sound that is there by default.

Let me know if one of you guys were able to change the alert sound in the new OSX Mavericks

Thanks in adavnce

Chris