First check whether you have enough seeders if there are about 20 or so (more is better) then you'd have to check your firewall and the routers port configuration ..specify a port for utorrent to use and unblock it on the firewall and on the router this is the safest thing to do or you can set utorrent to use a random port and you'd have to unblock all the ports(this is inviting to viruses, trojans..etc)