Tell us about yourself!
Do you have access to an oscilloscope? I've always had a lot more luck understanding what's going on when I can see what they're sending back and fourth. I have some experience with both PICs and the Raspberry Pi, but I've noticed that the PIC freaks out a bit more readily than a Raspberry Pi with i2c. Make sure that the speeds are set up accordingly (although this shouldn't be a problem with i2c). Another thing is, you could just transmit things over GPIO pins on your own. What are you trying to do? i2c may not be the only thing that can accomplish the goal you want.