2) The Remote Control operators are not part of a security group, it may be a Distribution Group.
2) Change the group type from Distribution to Security or Add them explicitly.
This can also be caused by the COM+ Objects, see http://community.landesk.com/support/docs/DOC-2094 for more information.
Error: Logon failed. You must provide valid credentials for a user in the 'HDAllowed Operators' group on the remote machine.
Cannot control because not a member of the HDALLOWED operators group.
1) Not a part of the Remote Control Operators (Local) group.
1) Added user to the Remote Control Operators (Local) group.