So a couple of things ....
I checked the logs and sure enough I was getting an "access denied" to \\server\share\myfolder in the UEM log.
My oversight ... I had full rights to the target shared folder but did not have any access to the DFS namespace.
So I then changed the UEM drive mapping to \\server\share\%LogonUser% and UEM give a Network path not found error.
I then changed it to \\server\share\%Username% and it worked fine .
Thanks
Chandlar