Unable to Add Map Services with Unsupported Coordinate System in GC REST Manager

Hi List:

I just installed Geocortex Essentials 3.4.2 and tried to add ArcGIS Server based map services with local (Ramsey County, MN) coordinate system. I received an error while previewing the selected map service: The ID "20211" is not the well-know ID of a supported coordinate system. I was successful, however, if I add map services of other spatial reference either from local or external GIS servers. Would you advise how I can make Geocortex REST Manager recognize and adopt our county's spatial reference?  Thank you!

Regards,