Reader range is too short.

Possible Cause:
1. There is a magnetic field near the reader;
2. The reader cable is not shielded;
3. The reader has been mounted on a metallic surface.

Remedy:
1. Remove the item which produces the magnetic field.
2. Use the shielded cable.
Confirm there is at least 100mm between the reader cable and any high voltage cables.
3. Remount the reader on a non metallic surface