Can anyone help me please? I don't know what's going on.

I'm on the 3rd part of chapter 16 book one, and I know I'm supposed to click on the third and last bottle. Right? But whenever I hold the chuột over it, the little hand thing doesn't appear over the potion vials. The hand shows when I hold it over the paper, but not the vials. Any advice? I can't advance until I finish this part.