When configuring a Connection in XenDesktop 7, you must specify the user name in the correct format, depending on the virtualization solution you’re using. If you’re setting up a Connection with:

•         XenServer – specify a plain user name; for example “username

•         VMware – specify a domain user name; for example “domain\username

•         Hyper-V – specify a domain user name; for example “domain\username

For more information about managing Connections and Resources, see: http://support.citrix.com/proddocs/topic/xendesktop-7/cds-manage-hosts.html