请教大神们根据系统自带的“双均线交易系统”屏蔽了做空的代码，怎么不能自动成交呢？请高手指教

Params Numeric FastLength(5);// 短期指数平均线参数 Numeric SlowLength(20);// 长期指数平均线参数Vars Series<Numeric> AvgValue1; Series<Numeric> AvgValue2;Events OnReady() { SetBackBarMaxCount(1+Max(FastLength,SlowLength)); } OnBar(ArrayRef<Integer> indexs) { AvgValue1 = AverageFC(Close,FastLength); AvgValue2 = AverageFC(Close,SlowLength); PlotNumeric("MA1",AvgValue1); PlotNumeric("MA2",AvgValue2); If(MarketPosition <>1 && AvgValue1[1] > AvgValue2[1]) { Buy(0,Open); } //If(MarketPosition <>-1 && AvgValue1[1] < AvgValue2[1]) //{ //SellShort(0,Open); //} }