tpsan

Hi newbie here, trying to install hikvision camera on dvr. I got all 8 channels working ,suddenly camera 1 option goes blank. if i go for single screen option -camera01 option is not even displayed.it shows only 7 cameras. if i switch cables its the same.only channel 1 of camera01 is disabled.Add IP camera is displayed on screen playback is possible of the chanel but no live view any help is appreciated

DVR model no i sds-7108 hghi-fi