The js validation works fine with j2.5.x and j3.3 and j3.4.0, but NOT with j3.4.1
So we had just to release a new version vm3.0.6.4. So just update VM to at least 3.0.6.4, we suggest to use always that most recent one. In case you are interested in the history, read here http://forum.virtuemart.net/index.php?topic=128952.0 or http://forum.virtuemart.net/index.php?topic=128961.0