Aleksandar

Hi all Can anybody give me some help about iVMS 4200 software. We have 64 cameras and time to time some of tham are out of function all we get is black screen and shows no video. Than we have no recording status. This happens very often nnd a company that sold us Equipment and Software are too fare and high costs to come every time when this happends. So im looking here for some intentioned help and I want to learn how to fix this problem every time. Thanks