If your L*E*O isn't recognizing the correct cards, the problem is that the bar code on the label isn't being read properly. Check each of the following:
1. With the back of the overlay toward you, there should be no space between the edges of the label and the left and bottom edges of the card.
2. The card should be exactly 11 inches by 6 inches. If it's too small it can shift in the device and cause a misread.
3. The printing on the bar code label should be clear and black.
4. The plastic card protector should be installed properly. The top, left and bottom edges of the protector should be tucked between the black case and the membrane, while the tapered edge on the right should rest on top of the beveled lip on the right.
If you have the L*E*O software installed, you can run the L*E*O software and see, at the bottom left corner of the screen, which card number the L*E*O thinks you have inserted. This can be helpful for diagnosing overlay recognition problems.