Since neither of you apparently read to see what you were getting into, I took a second to look up your answer:

"What happens if there is no more funds in hot wallet?
In that case last deposits will be cancelled and recycled back in to hot wallet. Remember to keep inviting after you join!"

Right from the site itself...

When it was time for your payments to be sent, the hot wallet was apparently empty, so the previous message was invoked.