My suggestion would be to test the airplane out with another TX-RX set, preferably 2.4ghz. It will let you identify whether its a radio problem or mode sickness (you know, new airplane... feels as if you are not in control but in reality you just dont know what you are doing)

Do if before you dig the airplane in. A plane in hand is worth two in the bush (wait... that cant be the right saying)

By the way, you didnt tell which make airplane, engine and servos you used

Ameyam