OSX: ofVideoGrabber - 'problems setting device'

I’m on OSX Intel 10.4.11 with QuickTime 7.4.5 (67). I have an InterView USB-XIVN-0599 with the EchoFX USBVision capture driver v1.30 installed. I can view the input from the camera both in the USBVisionCapture software supplied with the driver, and in iMovie, so the driver is working properly.

but in openFrameworks i get the following messages when i call initGrabber after calling setDeviceID(3):

listing available capture devices  
device[0] DV Video   
device[1] IIDC FireWire Video   
device[2] USB Video Class Video   
device[3] VideoGlide   
attempting to setup device[3] - VideoGlide   
problems setting device[3] VideoGlide *****  

debugging the code I can see that SGSetChannelDevice is returning an error. it semes to be ‘-1114’, which i can’t find any documentation about; but before it was very distinctly ‘-50’, which is the ubiquitous and informative ‘paramErr’.

any idea what might be going on here?