Are you exposing the emulsion side of the paper?
That is a possiblitliy. You would be suprised how many photo students at my school expose with the emulsion side facing down! If you are not sure which side has the emulsion, hold it up at an angle to your safe light. The side with matte sheen is the side you want. If you still cannot tell, lick a finger and touch a corner of the paper. The sticky side is the emulsion side... please don't lick the paper!

andrew