Singing in tune for recording... (instrumental, orchestra, tracks, show)

[DontRunMeOver]

My band is going to be recording soon and I've found that I have a very specific problem...

Usually, I sing completely in tune. Recordings from gigs, recordings I've done with an acoustic and vocals, piano and vocals etc. show that when pitched against a live instrument I rarely hit a bum note...HOWEVER...

In a recording studio (recording band music), the engineer tends to insist that I wear headphones through which the pre-recorded band parts are piped for me to sing along with in order to record the vocal parts. For some reason this causes a raising in the pitch of the music that I hear, I sing along with the pitch I'm hearing and when the vocals are played back they are always sharp (because I was singing along with a higher pitch than the true recording, or something like that).

If there is anybody else here who has done studio singing and who has encountered this problem? Is there any way to resolve it?

AND also, can anybody recommend a vocal instruction site where I can post similar problems? Anyone...?