As the challenge setter, you're the only one who knows for sure whether the challenge has been solved or not. At least, that's how it is in general - for this challenge it might have been OK to accept it and move on without confirmation. The thing is, I want to avoid the situation where someone posts a level and then it turns out it wasn't supposed to be their turn. So can I ask (this applies to everyone): if you post a challenge, could you please make an effort to check the forums and confirm/reject attempts ASAP?
And I was about to hand this over to you, Fernito, but I found a problem with your level that no one has managed to spot yet. You can turn the lemmings around by making them bash into the steel - see the attached replay. And, unlike the other issue with bashing through steel, I'm fairly sure this doesn't qualify as a glitch - just an intended mechanic used in an unusual way. See attached replay.
So, the next question is: does Pooty's level qualify? (Namida, you'll have to confirm or reject this.)
EDIT: It doesn't, see second attached replay. (At least I don't think this qualifies as "different paths")