I was trying to help a friend install a cable line to another room in his home. He wanted to move his cable modem to a bedroom from the den. I ran a new cable from wghere it enters the house to the bedroom. I then installed a bi-directional splitter from Radio Shack. If I hook up the modem diectly top the cable line it works perfectly. If I hook up the TV directly to the cable it works. If I use the splitter I can only get one device to work and not the other. Can someone tell me what I'm doing wrong? I don't understand this problem. Thanks