Seismic Parameters - Zip Code Not Found

Hello,

I was curious if anyone has encountered this error. I'm working on a steel structure to support pipes and electrical cable trays. The structure is located in a suburb of Phoenix, AZ (Eloy). The zip code is 85131. 

What I discovered was when I input the zip code and other seismic parameters into the code (see below), I get an error that says zip code not found!

DEFINE IBC 2012
ZIP 85131 I 1 RX 3.25 RZ 3.25 SCLASS 4 TL 6 FA 1.6 FV 2.4
REFERENCE LOAD Y
R1 1.0 R2 0.5 R3 0.5

What I found was that there are at least 6 other zip codes surrounding that one that produce the same error. I was finally able to find one that worked (zip code 85249), but it baffles me that somehow STAAD doesn't know what a certain zip code exists!