I would offer you a suggestion about how to do that but i wouldn't have a clue as to know where to find the leak,but we have a sleepout here and a few months back i found a leak in the roof the way i found out, it was raining one night and was raining pretty hard i didn't think anything of it that night but i went to sleep and woke up to see that it was raining inside the sleepout, now if you haven't clicked to any of that, in plain words i found out there was a leak in the sleepout because the water was pouring down on my face which woke me up lol.
So my suggestion would be to wait till it rains and maybe you can see where it's dripping from.