Wish I would have seen this thread earlier! I spent about 2 hours trying to get the sensor and computer to pair, moving the magnet in various positions, etc...it was definitely the magnet that was the problem. I didn't have any older (and/or stronger) magnets lying around, but I did have another "newer" Trek magnet from an 8i I returned a couple days ago in favor of the Link/Speedtrap combo (forgot to put it back in the box - woops).

I just stuck both magnets on the spoke side by side near the bottom of the sensor. Low and behold, it worked! So, if you have 2 crappy Trek magnets you can use both of those together and the Speedtrap should pick them up...did for me anyway. I will probably just get a better magnet and replace both of those next time I swing by my LBS, but for now my computer is working.