Then that is probably your problem.
Ruipro are the go to guys for quality hybrid copper/Fiber optic cables.
This is what you need, and what I have.
These cables are directional as there is opposite conversion at opposing ends. So pay attention to the arrows.
You will also need a
voltage inserter, or you will blow up your HDMI board.
So with an HDMI cable that length that is the gear you need.