One thing you can't do is use my v4v.app site to try to send lightning to a @v4v.app lightning address. That would be self payment and apart from giving me double commission it would be silly.

If you can send me a screenshot or a capture of the Javascript console I'll try to help.

If you just want to play I recommend Wallet of Satoshi for holding a bit of Lightning. I have a direct channel to their node so fees are usually 0 sats.