Some devices which do allow OTG may not provide a powered connection, which can be a further limitation. However, for an item such as a camera, simply turning it on might get around that difficulty. Also, is the camera OTG compatible? I'm not sure, but maybe it's needed for both?
Into the bargain, I have a very recent phone which in theory supports OTG, but requires me to authorise it on the OTG memory stick I'm trying to connect to the phone. It shows me an illustration of what I need to do, but I haven't yet figured out what it means!
