>I have a cable tester.If your tester is simply one of those continuity testers that does nothing more than check that the correct pins are connected, it does not adequately test a twisted-pair network cable and guarantee that the cable will work. For one thing, it does make a difference which wires in the cable connect the pins. If you have someone in a local shop make (http://duxcw.com/digest/Howto/network/cable/cable1.htm) you a crossover cable, suggest that you insist that they properly test it before leaving the store.
http://duxcw.com/faq/network/ends.htm
http://duxcw.com/faq/network/catest.htm
Larry