Thanks for your reply, I am in fact using production computer protocol.
I have changed the range to 100 and I am not getting any errors as I execute the command, just an instant jump to the value and no fade to value.
I have tried what you suggested with the same results as before, an instant jump to value.
the reason for the long fade rate is because I was testing over the top durations as I am always getting an instant change.
This has been puzzling me for a while, as the documentation is very clear and don't understand why its not working