Your username: jovanhon In which minigame/server does the bug occur: factions Video explain it: Watch the lvls to combine
Happened to me a lot when I was using 1.8. If you are using 1.8, try using 1.7 instead, 1.8 has a lot of bugs.
This is because you might've used it and the "health" bar didn't show up. When you combine a damaged item, even if it's 1 hit, it costs more levels to improve it.
I clicked it so many times, there is no way that the "health" bar did not show up. I will go and check again. Thanks :)