MS SQL: can not edit some tables values


I am trying to edit data from the table view. I can edit some tables and some are read-only.
I have checked Options:
Grid -> Edit on Single click - on
Grid-> Show data read only - off
Explorer ->Allow Editing of schema or DB list - on

And still there is a problem with editing. When I log in with the same user directly to MS SQL 2000 I have no problem to edit this table…

Please help