Here's a complete answer quoted from the official BitTube subreddit:
"I want to use the latest TUBE GUI wallet. How do I restore the coins from my old IPBC wallet?"
Safely backup the private key and/or mnemonic seed in the old wallet. Always do this. Download the latest BitTube wallet here. Import your private key or restore from mnemonic seed. It will ask for a file path; this is the path it will save a new wallet file to. Alternatively, you can open the old .wallet file located in %appdata%\ipbc or copy it over to to %appdata%\bittube (recommended).
Note: after the hardfork on July 2nd, you'll need the latest wallet to spend your coins. Updating is mandatory at that point.
The wallet you tried was the one released 2 days ago?
https://github.com/ipbc-dev/bittube-wallet-gui/releasesJoin their Discord Channel for technical support:
https://discordapp.com/invite/d4c89Vn