Minstrum, I had a problem with the lemon, too, and it turned out to be a matter of timing and clicking in the right spot. If you click to the center of the space where the lemon goes, you can get it in there, if elsewhere it just goes back to inventory. It took me about 20 tries, maybe more, before I gave up and asked my more coordinated partner to do it.
Of course, he got it in one!
"So then he says it's enough to take aim! What's that supposed to mean?!?"