10meg might be too high, but go ahead and try it, it'll either work or not, I'd try a 1meg next, and then if that doesn't work try adding more 1meg's in parrallel. 2 1 meggers in parrallel will give you 500k, three will give you 333k four would be 250k etc.. If you get down to 250k and it's still not doing anything batdin is probably right and the sensor is detecting the current, in which case you'd have to slowly add more resistance starting at 100ohms till you found the threshold of the sensor and then back it off a bit. Or if you're okay with it, just use the high power 100ohm resistor.