Ok, 9 years too late but I've found a pretty ugly workaround for this one Bane.

Add a new combobox on your form and set your Dlookup to autopopulate this new control on the form, as Scott mentions. Then, once it is working, you can delete the control from the form and the Dlookup will continue to work in VBA.

An inelegant solution but it got me out of a hole so hopefully it can help someone else.