Lensbaby and the RP

Jan 31, 2016
A friend has lent me his lensbaby for the summer, but my RP doesn't want to have anything to do with it: the shutter release doesn't do anything at all.

My hypothesis is that the RP doesn't detect the presence of the lens and refuses to take a picture. I didn't find anything in the preferences menus about that; I can take a photo without a card (!), but not without a lens.

What do you suggest I do?