You may not have permission to perform this operation, or the object <Os> may no longer exist in the database.

The object you want to work with may be listed, but you may not have SELECT permission to this object. Or, the object may no longer exist in the database.

Refresh the list of objects to find out if this object still exists in the database. If this object still exists, then contact the owner of the object or the Database Administrator to get permission to this object.

For more information, see Ownership of Database Objects.