If he already has  2 working PATS keys in possession with unique IDs that start the vehicle , then if he hasn't already reached the maximum  8 keys registered, he shouldn't need PATS security access with his Maxi Sys to add an additional PATS key. Remove the VCI and turn off ignition and remove key. Do not have all the keys together on same ring . Take the first programmed PATS key and turn key on 3 seconds until the theft light goes out, immediately turn key off and remove it and quickly insert the second programmed PATS key and turn it on for 3 seconds until the Theft light goes out , immediately turn key off and remove it and quickly insert the unprogrammed key and turn key on until the theft light goes off. Then the un-programmed key should now be programmed and be able to start the vehicle.