Getting problem connecting to a WebDAV server.

My Windows 7 can't connect to a WebDAV server. An error message is showing up when I try to connect with a WebDAV server. Can anyone please solve this problem?
Open Folder
\files.riverdale.edu@SSLDavWWWRootadmin is not accessible. You might not have permission to use this network resource. Contact the administrator of this server to find out if you have access permissions.
Multiple connections to a server or shared resource by the same user, using more than one user name, are not allowed. Disconnect all previous connections to the server or shared resource and try again.
OK

