[otrs] Can't see tickets sent in a sub-queue

Hi When I create a new ticket and that I send it in a sub-queue, I cannot visualize it in the interface agent whereas it works with a root-queue. I can just see in the QueueView that a ticket arrived in this queue. But when I open this queue, no ticket is visible. I checked out all the possible modules or options related to queues. Also groups and users settings look good. Can anyone give me a clue to solve this problem Regards Martin DAUGUET