Thank you for the quick reply, Patrick.
I am aware of the 5M USB limitation, as I did some research before buying this extender, but went with the company's word that it did transmit power.
While the InterfaceKit is having problems, the extender works fine with several other devices. A mouse I tried worked fine. A powered device I tried registered as attached, but would not work due to the lower speed standard (the cable is USB 1.1, it needs USB 2.0 -- but the fact I got a spoken error message tells me the computer picked it up fine). So the extender seems to be working.
What types of extender have you seen work fine "in many cases" before? I would appreciate any tips, as I need to make this arrangement work by this weekend. In the meantime I can certainly try your suggestion of a powered USB hub (I'll need a short male-male USB cable too, I guess, as the extender has a female end).
As a backup plan, is there any other way to attach power (adapter, etc.) to a #1018? Is a #1019 completely self-powered by its adapter, and thus better in these situations?