Garmin 310xt and Speed/cadence sensor question...

WCTri - 2010-09-14 8:12 PM Alright I have the 310xt and the garmin speed/cadence sensor. I just got the sensor thing and i hooked it up but the little magnet you put on the pedal i did not attach because it was too far from the sensor and it would not pick up. So i just have the sensor itself and the magnet attached to the spoke.   I press the reset button on the side of the sensor and it flashes red and then as i pedal it turns green each time the magnet passes the sensor.  I already paired the sensor and the 310xt before I set things up.  My garmin 310xt when I turn it on is already paired with the sensor and when it turns on it automatically buzzes and says speed/cadence sensor detected. 

I'm inside if that matters and I hop on my bike and begin to ride. I press start on the garmin for the timer to begin and no speed shows up.  The sensor is not flashing green as the magnet passes the sensor. In order for it to flashes green as it passes it I have to press the reset button on the side.  Is the battery dead? Why isn't it picking up my speed? Do i need to get another bike computer for inside? Are the settings not right on the sensor or something? Do i need to put that magnet on the inside of the pedal (thought that was for cadence)? I just want to know about how fast I am going speed wise when I am on the trainer. 

Thanks in advance!