Bad luck there. As it has been said several times here the only plug & play CD changer that would work with the original head unit is the factory one, although some have theorized that another CD changer from the same manufacturer (Fujitsu Ten) should work.

Unless you're able to find a good offer on an used factory CD changer (not an easy thing: It took me more than 6 months to find one within my budget ), an after market CD/MP3 player or an IPOD-like device will be the way to go.