Hi Mike,
you can't use a variable in a query criteria.
This is a Workaround:
Make a function in a module like this:

public Function GetDeleteID() as Long
       GetDeleteID=DeleteID
end Function

In the query use the Function GeteDeleteID() instead of DeleteID

UPDATE  YourTable Set FieldX=YYYY  Where ID = GetDeleteID()

Cinzia

Enter the criteria with brackets around the item, so Access will know you
are referring to a field.

Criteria: =[DeleteID]

To be extra safe
Criteria: =[Your Table Name with DeleteID in it].[DeleteID]

If the criteria for the query is a field in the form, you should use

Forms![FormName]![DeleteID]
=============================
The thing that pazzle me, if the query change automatically to "DeleteID" it
mean that the field type is string, and you said that the field type is
number.