Form using autonumber field for selection and updating

[Budatlitho]

Hello:
I have a table, Orders, whose key field is OrderID. The Data Type is AutoNumber.
Another field in this table is ShipmentID
I want to display the record by using a Combo Box, whose RowSource is from a query, OrderListQuery, that limits OrderID to records that have not been shipped (ShipmentID Is Null)
OrderListQuery:

SELECT [Orders]![OrderId] AS Expr1, Orders.ShipmentID, Orders.ShipDate, Orders.LabelId, Orders.Quantity, Orders.OrderDate, Orders.DeliveryDate
FROM Orders
WHERE (((Orders.ShipmentID) Is Null))
ORDER BY [Orders]![OrderId] DESC;

Combo Box query is:

SELECT [OrderListQuery].[Expr1] FROM [OrderListQuery] ORDER BY [Expr1] DESC;
where Expr1 is OrderID.

OrderListQuery displays the desired data.
The Combo Box displays the desired OrderID data.
However, when attempting to populate the form using the record selected, it errors in that OrderID cannot be set because "control cannot be edited; it's bound to autonumber field "OrderID""
Form is set as Data Entry: No.
The record selected is OK, confirmed with:

Private Sub Combo27_AfterUpdate()
Debug.Print Combo27
End Sub

but I cannot get OrderID in the form to accept Combo27 value.

I believe I could write VB to select the record and update it but it seems like the form should be able to accomplish the same action more easily.

Hopefully, I'm missing something really dumb, but the hair color of my mustache is beginning to change to that on the top of my head- GRAY! (grin).
Thanks in advance.

[NTC]

first let's start with .[Expr1] ...that is a default field name due to a duplicate field name or missing field name. Do yourself a favor and establish a valid field name.

moving on: a form is bound to its record source which can be a table or query. A query may be not editable. This is a standing principle in query design whenever the query is not a 1:1 relationship between table's primary keys.

So in the form, your selection of the correct record (i.e. not shipped) is a query within the combobox which results in the bound OrderID record that the form moves to - whether or not the form's record is updateable is dependent on its record source query.

[Budatlitho]

First-- thanks for the quick response.

I removed the query that restricted the records to 'not shipped'.
So now the combo box displays all records by OrderId.

SELECT Orders.OrderId AS ID FROM Orders ORDER BY Orders.OrderId DESC;

debug.print shows correct record.
When attempting to assign OrderId control as combo box value, I get
Run-time error, '-2147352567 (80020009)': You can't assign a value to this object

[NTC]

it would seem that you have built your form incorrectly somehow. I presume you have a form that uses table Orders as it's record source.

if your form is in continuous mode (displaying lots of records) then traditionally the selection of a record is not via a combo box

if your form is in single mode (displaying a single record): delete your existing combo box; drag a new one into the header of the form and follow the wizard set up to make the combo box select a record