One of the many weaknesses of the AP site is it does not display all possible routings to you, and may want to keep you on AC metal.

For example the AP site may only be looking at direct YYZ-FCO flights while ignoring connecting through FRA or MUC. Or going via US airlines out of ORD etc. Your best off using a tool like KVS, or signing up for a ANA frequent flyer account and using there award search engine to check availability.