gazzabazza

Hi All, total Newbie here so I hope I don't offend anyone. I'm totally new to networks and CCTV and bought a Grundig 8 channel NVR with a collection of IP cameras all PoE. Some of the cameras are Grundig Cameras and these connect no problem at all, but the other Cameras ( 1 x Hikvision and 2 x Ebay Jobs ) wont connect. Can anyone guide me through what I need to check to make these other cameras work? Thanks in advance Gary