[amibroker] backtester doesn't work on indices?

[reydontrader]

I try to run backtester on indices and it doesn't give me any return.
could it be the missing volume caused the backtester not to run?

Below is the sample of the simple formula:

MA1 = MA(C,20);
MA2 = MA(C,5);

Buy = Cross(MA1,MA2);
Sell = Cross(MA2, MA1);

thanks.