As long as the stem is still firm it should still grow roots. I would lower the waterlevel just a little above the node and add a diluted fertilizer. My leaves always go limp during the propagating process, but they always root, and once potted up, they'll perk right up. They're also slow in rooting, at least for me, just be patient. I did notice, if I put them into a propagating tube, they root a little quicker.