Non Responsive Network

I’ve connected 3 computers in a network with a hub, rj45 connectors, realtek nic’s, utp cable, 2 x13m and 1 x 3 m. I use a workgroup 2 workstations have windows 98 and the third Windows 2000. I’ve setup “client of microsoft network” use Netbui as protocols. Use unique names. The computers does not “see each other” No valid link available! How can this be. Originally it connected very slow then stop totally. I can’t seem to find the problem, what is wrong?