All three of the apps you mentioned support the ANT+ bike speed and cadence profile, so chances are that your sensor is not broadcasting its data.
1. Make sure that the sensor is an ANT+ sensor
2. Make sure that the battery is not dead
3. Make sure that the magnet is passing the sensor correctly. You should hear a click sound when it passes it
4. If you have an ANT USB Stick you could use the ANT+ sensor and ANT+ display tools (found here http://www.thisisant.com/pages/ant/ant-simulator-tools
Note that you must be an ANT+ Adopter to download them) on a PC to help troubleshoot