I have a box of bulk Cat5e riser cable left over from when I had my house wired. I figured I could use this to make some custom length cables for connecting my computers, switches, etc. I had a crimper already so I bought a bag of RJ45 plugs. I made a few cables several years ago, but my experience/knowledge with this sort of thing is minimal. None of my cables are working. I don't have a tester so I just plug the cable into a computer and switch but I get no link light. I wired them them all straight-through and visual inspection doesn't show any problems. Any ideas what I might be doing wrong?