I already test it and it's working.
I haven't the first bottle at level two or a second bottle and I can't buy the spell, so Cloy tells me the message you said, but after buying the second bottle, the Cloy's message changes.
I don't know if you are using an old save (save file of a version 0.20 or older) that allows you to store more sexual energy than 50 points without buying the second bottle, but it may be the cause of your problem. But anyway, using an old save or not, buying the second container should work.