ORIGINAL: eddieC
The receiver is not getting any signal.
If it weren't getting any signal, the servos wouldn't jump around. It's not getting a good signal, or not decoding it properly.
Sometimes a light tap on the receiver or trans will reveal some signs.
FM radios don't "decode" a signal. "Modulation" is the word.
And, many older systems don't incorporate failsafe, to return servos to a preset position.