All hall efect sensors sense a magnet pole. The response (output) to the magnet pole depends on the type of sensor. A unipolar sensor like RCEXl uses responds to either pole depending on the orientation of the sensor itself. You have the correct sensor. It's very unlikely, but possible, the magnet you have is magnetized incorrectly.

OK, I just reread your posts, and see that your magnet is chipped. Replace it. A chipped or cracked magnet creates another set of magnet poles in the magnet.