When installing security devices into AHP/OnAlert, you have to make sure no other security device sends a signal before you make the intended device send its signal.
For example, if you are installing security remotes and you are sitting in an area where a MS10A motion sensor can detect you, most likely you will get the incorrect signal being registered for your device.
When you run into a problem like this, you are better off unregistering the security device that says it is already install because chances are it is incorrect. But do keep in mind that there is a 1 in 64K chance that two devices have chosen the same security code; so if all else fails, reset one of them.