Back light not workng, replaced laptop LCD, next step?

Question

My daughters laptop LCD went dark a while back, in a dark room you can see that the screen wants to work but will not. I am familiar with laptop repair, have replaced MANY screens. It seems I have been lucky to have the same fix work each time.

I did my usual routine for diagnosis by plugging in an exterior monitor, which worked. So, bad LCD, I figured. Ordered a new LCD, got it, installed it and no video, or should I say the same issue with the original screen. So I ordered an inverter for the laptop, exact type, tried it, no good, same issue. I returned the LCD screen for an exchange, got another one, tried that, still the same issue. I know about the connector issues, and I have been now even more watchful how they go, since I did a second teardown and reconnect on one, a Toshiba, I worked on a few months ago, just to find out it worked after reassembly.

So, bottom line question is, since the only obvious thing left to change is the video cable for this Toshiba laptop, could there be anything else that would cause the same symptom I describe? What throws me on this is the screen works, just not backlit. So if the cable is bad, then just that wire that the inverter is on must be damaged.... just guessing.

Secondly, how likely it is that video cables are at fault? Seriously, I must have changed at least a dozen or two dozen LCD screens over the years, (its a hobby for me) so for me it does not seem very probable at all. I have seen in this site that there have been others with the same problem, bad cable, but there is not way to tell based on that. The most reliable way to know would be of somebody else's experiences, since this is my first go at it.