Setup to use Style property of WMS?

I can see in the essentials restmanager that there is a drop-down to set STYLE of WMS Layer.   https://GEOCORTEX_SERVER /Geocortex/Essentials/RestManager/Help/RM_HelpFileWEBHELP/Ess/RM/RM_OGC_WMS_Configure.htm

The drop-down is blank for me, but the STYLE i want is available via ArcMap...

Anyone use this function? Am I missing something, or does this not work? 

The style i want shows timestamp for imagery data, would be nice to have, not a show-stopper though.