It could be that the hole where the valve feeds though is kind of sharp. Had a rim set that came like that once. Take the tape off and use a reamer and gently rotate it around the hole to see if you feel any sharp edges while doing this. You could also go to the autopart store and buy some 400 grit paper and roll it up like a cigarette and put it in through the hole and gently rotate it as well. I think you have a sharp edge some where in there.

Here is a pic of the reamer in case you're interested.