It looks like this problem is being reported by many people. One post estimates a 1:4 failure rate for Hikvision units in powering up, and the same problem is reported with many models of POE gear.
My only suggestion would be for you to power up other 802.3af units from the OmniTik port and satisfy yourself that the Hikvision is the odd man out. And then perhaps try to power up the Hikvision from other models of POE-out switches. I know this isn’t the easy solution you want to hear.