Faulty Network Cabling

I spent most of my Monday night with our network cabling contractors trying to fix one of the strangest networking issues i have ever experienced. We ran 5 points to a new office, using cabling supplied by a company called Yodata we never used before. After the installation, our contractors tested the points as per usual and everything seemed fine. While they packed up and left, myself and a colleague moved 2 workstations to their new locations, only to find Windows complaining that the network cable is unplugged... After more testing (the cable tester only tests continuity) we eventually figured out the (brand new out of the box) cable is completely poked. 

I still don't know exactly what why we dont get any comms across, tonight we are installing new cabling. That works.