Queries :: Unable To Copy Records Into Another Table

I'm using Access 2007.

I have a button on a form that when clicked, does the following:

I have a table called [Workorder Parts] that has 128 records in it with Fields named WorkOrderPartID (Autonumber), WorkorderID(Number), PartID(Number), Quantity(Number), UnitPrice(Currency), Notes(Memo), KitID(Number).

I want to copy records into another table called [tKitsWorkorderParts] that has the identical structure based upon a value in the field WorkorderID. For testing purposes let's assume that the field contains the value "12". There are 28 records in the table that have the value set to "12"

If I hardcode the value "12" into the following SQL statement, it finds and copies the 28 records correctly.

DoCmd.RunSQL "INSERT INTO [tKitsWorkOrderParts] SELECT * FROM [WorkOrder Parts] WHERE [WorkOrder Parts.WorkOrderID] = 12"

so far so good.....

Now, on the form there is a Text Box called WorkorderID that contains the value "12".

If I change the code to the following, I get all 128 records instead of just the 28 I am expecting:

DoCmd.RunSQL "INSERT INTO [tKitsWorkOrderParts] SELECT * FROM [WorkOrder Parts] WHERE [WorkOrder Parts.WorkOrderID] = WorkorderID"

I have inserted a few MsgBox displays to display the value contained in WorkorderID and it shows "12"...

What am I doing wrong???