Qualia may or may not exist, but you are forbidden to claim that introspective access is dispositive in regard to the question. This is because if you take away the hypothesis of an inner witness (since it is supposed to lead to an infinite regress) then the act of examining your experience is an entirely different act than that of simply having the experience. Of course the two acts are intimately related, they are not merely arbitrary accidents of being, but their relation is perfectly accounted for by the functional account of consciousness - namely, that it manufactures a practical account of whatever is in attention, preparing reasons to explain if called for, for example. The functioning is self-reflexive, but in a finitistic sense only. It is computational laziness that leaves this fact vague enough as to be subsumed by the idea of a fully self-reflexive event, and hence leaving the door open for the illusion of a transcendental witness. But isn't this argument based on the inverse error to that of the detached witness?