The ETS/office of disability policy statement on diagnosing ADD states that, "Cognitive and achievement profiles may suggest attention or information-processing deficits. No single test or subtest should be used as the sole basis for a diagnostic decision." They do include the IVA+ as one possible "attention, memory, and learning" test but I'd take their statement to hold the converse as true as well: if no one test can absolutely diagnose AD/HD, no one test can absolutely rule it out either.
http://www.ets.org/disabilities/documentation/documenting_adhd
