Futaba on Model-Helicopters.Com

I have a T-REX 450X with XL upgrades, the problem i,m having is, i turn my tx on connect the heli battery and wait for the ESC to go through its course, i then push the throttle stick and let the rotor spin just to the point of lift off and when i throttle down the blades are still at the same speed even thou the stick is all the way down but if i throttle up still with the blades spinning as soon as i push the stick the throttle snatches and is controllable and i can throttle down as normal.
All the controls function as normal on the range / pre checks, any ideas please.

possibly a dodgy speed controller,did it work ok with a 35mhz transmitter?

It does sound like a speed controller issue rather than radio. Have you tried resetting up the speed controller?

Thanks for the replies, its all new, ESC, everything, the 2.4 is the first rx, this problem only happens indoors but when its in the garden its fine, anyone in leicester who could have a look at it please.