Learning the Berkeley Alpha DAC remote

Has anyone successfully learned the Berkeley Alpha DAC remote codes? I have tried 2 very different "learning" remotes, the Philips Pronto Pro and Zenith ZC600, and neither were able to learn the Alpha DAC's 'input' button. The learning operation proceeds as expected but then the learnt button does not perform the function. Within the ProntoProEdit program, the learnt hex codes are correct. Thinking the problem could be timing, I varied (+/-) the pulse timing from within the ProntoProEdit but this also had no effect. Any ideas?