[AccessD] A2K: Error 3251

Hi All
This should be simple

I have some code updating a table of records

    Dim selSQL As String
    Dim rs     As Recordset
 
    selSQL = "SELECT tblMyTable.* FROM tblMyTable;"

    Set rs = db.OpenRecordset(selSQL, dbOpenSnapshot)

         With rs
             .Edit  <===Code Fails Here
             !MyField = Me.txtMyControl
             .Update
         End With

The rror I get is...
Error 3251: Operation is not supported for this type of Object

Any suggestions??

Many thanks

DArren