HDX cannot mount NAS

I am using a Drobo 5N. Shared a folder HDX. Admin has full rights to HDX folder. When I add a network share to the HDX, HDX gives me a "Unable to add Network Share. There is already a connection open to this host that uses a different user name and password." I have successfully manage to connect to this Drobo 5N HDX folder from my WIN7 notebook and Mac OS 10.8 (using afp and smb).

Help someone please......