Well, I've not seen that particular iPaq. I might think that there would be more information on pocketinsanity.com. That said, though, have you used UAE before on any systems? If so, are you sure you have Kickstart ROM images that are valid? Are your paths valid? Can you get a kickstart 1.3 screen up, if you mount no disks?
As far as I know, PocketUAE is the only Amiga emu for PDAs.
Also, if your model really is the iPaq h1920, it has two strikes against it from the start. It would be a Japanese/Chinese market item, and it features a 200 mhz XScale. UAE barely runs fast enough to be useful on my iPaq 4155, which features a 400 mhz XScale....