They arrived on Aargau without problem since there was little in the way of security checks done on inbound travelers. However, since everyone leaving the planet had to go through scanners in order to prevent theft of Aargau's precious metals, Leia had to find a way to avoid having the droid detected since if the ruse were found out, the transaction would be voided. She accomplished this by luring Darth Vader into attacking the droid, "killing" him during their visit.