Magnates made a few years ago have adhesive that will allow slip. Check with magnate template (blue). Tape should be marked for template at each floor and for slow down positions. Pay attention to polarity (groove down face on one side). Make sure you use correct lane on template.
Two options:
1) Replace all magnates with new. Clean all old adhesive from tape with alcohol or solvent.
2) clean adhesive from tape and magnates. Use a drop of super glue at top and bottom of magnate (about an inch from end; drop in center will not hurt) put back in place.

Tape guides will also cause this error. If they have not been turned you may still have a a new guide surface to use. Keep the tape reader suspension free and clean.