Concur uses a format for regional codes that comply with ISO 3166-2-2007 standards. 

You can find the regional codes they use here:
https://www.iso.org/obp/ui/#iso:std:iso:3166:-2:ed-2:v1:en 



Chances are that in Deltek's Code tables, the codes you have entered may not match up to the ISO standard that Concur uses - you can verify this by browsing to Configuration > General > Code Tables and click on the State/Province item: