I'm sorry to hear you're experiencing this issue.
We offer no special support for DevExpress controls. But you should still be able to automate them just like any other HTML-based UI widget.
Could you please provide as much information on the problem as possible:
In particular go ahead and send us the test and a recording of it running (Jing is a great piece of software for this).
Most likely some event that's attached to the dropdown is not getting fired by the automated test. jQuery might be involved - in this case please try implementing one of these solutions:
Hope to hear from you soon.
the Telerik team