2002 Honda civic Cd changer w/ stock radio hlp!!!

I recently bought a alpine chm-s620 online for my 2002 honda civic LX. The reason i bought it was because a salesman at a car audio store (ill call them TAS) told me it would definitly work with my cars stock stereo. now i make an appt. and go to another TAS location (theres multiple around here) and im told that this cd changer wont work with my stock stereo. whats up with this? why would two stores tell me two different things?. somebody please tell me whos wrong and who is right. thanks

Metalix