Trailfan

Hey there lads, hoping one of you can help with this as we've tried everything. We have a Lorex CVC7711 960H camera system that we are trying to pull footage from. We have been using a USB external hard drive but whenever we back up footage onto the hard drive and try to read it on the computer, it comes up with only a few KBs of information that we can't open. We're convinced we're doing something wrong. Does anyone know where we're making the mistake? We'd appreciate any advice!