i have had leaks in the past.
I experemented with different appliances and also made sure i was getting a good fit around my stoma
Another thing I do is cut the hole in the wafer a little off center, so that it moves it away from my belly button. If I cut the hole right on center, the edge of the wafer would cover my belly button and not allow for a good seal.
I also wear a two piece appliance and snap on a fresh pouch every 3-4 days.