This just happened (well, 3 hours ago) and I feel compelled to share.
I just got my first IP camera and I went to install it at my house.
I have Cat5 wire sticking out of the wall, but didn't know where the other side was terminated so I asked my new helper to put the alligator clips on each one of the 8 wires and connect it to the tester/toner that I have.
[Link: specialized.net]After he successfully found the other end on port 44 of my patch panel, I asked him to put the 'remote' of the tester into port 44 and see if the tester gives us a passing result for pin-out and continuity.
He told me that tester showed 'open', to which I responded that he must have had the wrong port on the patch panel.
He went back and forth 3 different times to switch mode on tester from test to tone mode and each time port 44 toned as the strongest signal.
Frustrated, he told me that he gave up and didn't know what was wrong.
After putting ankle, knee and wrist braces, I grabbed the crutches and picked up my broken ass from the chair and stumbled over to the wall where the cable was hanging.
It took me a minute to realize that my helper never stripped insulation from individual conductors!
Probe/tone worked thru insulation, but continuity obviously did not.
If you gave me 10,000 guesses as to what could have caused the issue, I don't think I would have guessed that one :-)