Problem with AC + DC Power Injector

I have an AC + DC power injector, when the AC is connected, the green LED flashes and stays on. When the LAN port is connected to the PC, the yellow LED flashes rapidly 3 times, this does it ten times and then it turns off, at this moment it can not be connected to the ODU. What could be the problem?

NOTE: the ODU and the UTP cables are OK since the AC + DC Power Injector was replaced and there is connection to the ODU.