Well, that's a pretty discouraging comment isn't it?

GreenAce, there's nothing wrong with your sub, toy subs like those can only handle so many functions at a time due to their on RC-boards. This is due to the fact that there isn't enough power coming from the batteries as the signals gets weaker from extended range, operating two motors at a time also requires a lot of input power. Many people have fixed this problem by installing batteries with a higher amp-hour rating such as 2800 mah. You can also extend the antenna for longer range.

Check out the Walmart Submarine=Cool! threads for more details.