The problem may be occurring for one of the following reasons: 

• It can be categorized as a P.O. Box ZIP Code. P.O. Box ZIP Codes that have an equivalent street address delivery ZIP Code were eliminated from PC*MILER 22 and newer versions. P.O. Box ZIP Codes that do not have an equivalent street address delivery ZIP Code (such as Grand Canyon, AZ) were retained in PC*MILER 22 and newer versions.
• It could be discontinued by the USPS and therefore no longer accessible in PC*MILER. 
• It could be a new ZIP Code that will be added to PC*MILER in an upcoming quarterly data release. 

Freight to be picked up from or delivered to a USPS facility should be routed using the street address delivery ZIP Code for that facility. PC*MILER 22 and newer versions include all ZIP Codes for which physical pickup or delivery of freight is possible.