I'm new to drones and FPV and I've look everywhere to find an answer but can't

I have a phantom 2 with a H3 3D gimbal and gopro hero 3+ and a 5.8ghz TX Immersion 250w... and a seven inch Black Pearl monitor

When powering up through h3 3d all I got was a black screen on the black pearl...

I thought i might of blown the tx or have a bad cable.... so I bought another immersion TX and usb cable for H3 3d to the Gopro, still nothing.

So I have now bought a direct usb to TX cable which takes me start from the Gopro to the Video and ground of the immersion TX and I'm still powering the TX from the phantom. (The gopro now self powered)

Now when I turn on the phantom... nothing just a black screen...

but at last when I turned the Gopro off and on I suddenly got full video on the black pearl for about 2 seconds... then it went black again.....

I now know the new leads working, the TX is transmitting and the black pearl is recieving, but only for 2 seconds

I tried the old tx, that works the same, nothing until I turn the gopro off and on and then only 2 seconds

Has anyone got any idea whats going on

Steve

its not 250w its 25 mw