Hmm. That it works at all indicates that the numeric value being sent is correct, so I would think this would be a protocol problem. But all my sources for Cambridge/Creative speaker system config files seem to agree on the protocol, carrier frequency, and duty cycle values, and I seem to have all those set appropriately. (And, since you've already checked the frequency and duty cycle yourself, we can probably rule that factor out.)

Let me ask, is your copy of Pierogi having trouble with any other devices? (Assuming you have other devices with an IR interface.) Maybe something is causing it to act up...