A lot of guys that do good on Vibes and Heddon sonars are " force " feeding them. Which is a polite term for snagging. Observation will give you an idea just as to how a particular fisherman is working his vertical bait. Real long aggressive snaps upwards on the rod means that they are relying on snagging one.
That being said there are lots of walleyes caught legally on these vertical jigging baits. If you have caught a few crappie on them you are doing something right. Perhaps your location isn't productive for walleyes. If you see another fisherman using sonars with 12" to 24 " medium or slow upsweep. He is probably doing it right.
If he has a few laying on the ice ask him to show you how to work them. Make sure he knows you aren't going to set up on his fish. Though he may invite you to join in with some first hand schooling.
I don't often fish for walleye but a vibe is one of my preferred lures when I do. In my experience they take it on the drop or pause. Watch your line closely if it zigs to either side or goes slightly slack for no reason set the hook. Some times after a pause you will feel extra weight as he has taken it on the pause portion of your cycle. Sounds a lot harder than it actually is. I have taught rank beginners out on the ice in less than 20 minutes.
