I'm trying to switch my dd onto anyway up cups, but when I tried them this afternoon (I've got 2) they both leaked. Not from the spout, the valve obviously worked, but from the top - seemed to be leaking at the point of the end of the screw thread and both cups I've got did it (I think one is a 4 month and one a 6 month cup, but both same colour and can't tell the difference). I bought them ages ago (dd wouldn't suck strongly enough at the time) and I've thrown away the instructions (stupid, I know). Everyone says these cups are wonderful, so I can't believe both of mine leak and I wonder if I'm doing something wrong? I seem to remember something about priming them by pressing the top - do you do that to make it easier to drink from or the reverse and does this stop it leaking? Any advice would be great.