Would any one know why the telemetry cable all of a sudden stopped working, it still shows receiver voltage but no flight battery voltage, all the connections look secure, I just wired it up to a spin 99 and it was working and now its not. What could possibly be wrong with it.

Try reloading the sensor and re-register it in your transmitter.

Ok and how you do that

What radio do you have?

18sz

If you installed the fuse supplied with it, be sure it's not open.

It has the fuse installed, was working fine, can you use it with out the fuse or is that not advisable.

If the fuse is blown it did it's job and protected your RX from some unwanted current.

That's funny. I made my own cables and have flown them for years. They don't have fuses.
I'm not sure exactly what the purpose of the fuse would be. If the receiver fails in such a way to start drawing gobs of current, a fuse blow likely wouldn't save the plane. In the other direction, if the input line spikes or overvolts, the fuse probably wouldn't respond quickly enough. The receiver design should employ appropriate protection for that type of scenario, anyway.
A fuse is probably just a design feature that 'seemed like the right thing to do.'
Back to the OP's question, I've found the connector at the receiver to be unreliable and hold it in place with a drop of 5-minute epoxy.
-Ron

It was the fuse, I believe I blew it when I plugged in the motor batteries first then turned on the receiver after, my bad, live and learn, I put in a new fuse and now works as advertised.

Just wonder if high voltage from the power pack is optically isolated from the low voltage at the receiver side.

I probably hesitate to use it otherwise, since all the time each pattern flight is timed and uses fixed amount of energy from the pack.

Now that you mention it, jet, I have never, ever done that!