I would urge caution about generalizing as there are all sorts of disabilities that affect children in a variety of ways. There certainly are many 2E kids who scores as highly or profoundly gifted so it isn't easy to say all kids with disabilities will have trouble scoring well on IQ tests.
To the original poster, it certainly could have been related to disabilities but it could have been many other things - you may have been tired, didn't want to be there, a not great tester, etc. It is hard to generalize a lot from one set of data.
