Cannot edit this cell.
The cell you've selected cannot be edited. There are many possible causes, including:
The field is the result of a computed expression.
The field is a literal.
The field is part of a read-only joined table.
The field has a precision greater than 29.
You do not have update permission.
The recordset itself cannot be updated.
Previously run triggers or updates may prevent getting the current value.
For more information, see Modifying Columns (Visual Database Tools).