Please check these threads and 5-Minutes Lessons regarding the tuning of the Snare Drum. If these don't help or answer your questions ... please get back to me and I'll see what I can do.
I always tune my Snare drums so that the bottom head is tighter than the top head. Make sure the heads aren't too tight ... and also check to make sure the snare wires are touching the properly, with the right tension.
If all else fails, back off the tension on the top/bottom drumheads and start over. Sometimes this is the easiest thing to do if you can't seem to fine tune what you currently have.