A detector may flag genuine currency as suspect for several reasons. If bills are worn, bent, torn, or crumpled, the anti-counterfeit features required to verify authenticity may be compromised. For instance, magnetic ink may wear down over time or with heavy use, reducing the magnetic response below detection thresholds. If the 5520 cannot verify the expected features on a note, it will flag the currency as 'SUSPECT.' Additionally, dirty or damaged sensors, incorrect calibration, or operating conditions may lead to false positives. To minimize these errors, avoid direct sunlight and reduce potential interference. If issues persist under normal conditions, please contact Cassida Technical Support for assistance.