Like others have said, the standard for copper ethernet interconnects is 100 meters. Although in many cases, you can go over and have no issues, IP cameras often use UDP to transmit live video, where you give up the error checking and correction capability of TCP. This means, that any dropped packets, or chunks of dropped packets, will result in a noticeable video loss or interruption.
Using high quality Cat 6, connectors, and network hardware may alleviate the problem, but the only real solution is to run fiber or add a switch somewhere in the span.
This is addition to any VD problems others have already mentioned. PoE devices can be PoE or PoE+, which relates to the amount of power a port can source or how much a device requires to operate. Make sure you have the proper PoE injectors or switch for the cameras you are using.
Let us know what you find.