Math problem when calculating lots for a partial close

Hi guys,

this script should close a part of the running trade just to cover a possible loss if the stoploss would be hit.

For example I bought EURUSD at 1.1600 and the stoploss is at 1.1550. Price rises to 1.1700. Now I want to sell exactly the amount of lots that the rest position is safe in case of price falling down to my stoploss at 1.1550.

I hope that makes sense.

Here is my code so far. Everything seems to be correct until the very last part of the code where I try to calculate the lots to close.

void OnStart()
  {
//---
   for (int i=0; i<OrdersTotal(); i++) {
      if (OrderSelect(i, SELECT_BY_POS)) {
         if (_Symbol==OrderSymbol()) {
            double moneyRisk = OrderLots()*MathAbs(OrderOpenPrice()-OrderStopLoss())*MarketInfo(NULL, MODE_TICKVALUE)/MarketInfo(NULL, MODE_TICKSIZE);
            double pipsProfit;
            if (OrderType()==OP_BUY) {
               if (OrderStopLoss()>OrderOpenPrice()) return;
               pipsProfit = Bid-OrderOpenPrice();
            }
            else if (OrderType()==OP_SELL) {
               if (OrderStopLoss()<OrderOpenPrice()) return;
               pipsProfit = OrderOpenPrice()-Ask;
            }
            else return;
            double currentProfit = OrderLots()*pipsProfit*MarketInfo(NULL, MODE_TICKVALUE)/MarketInfo(NULL, MODE_TICKSIZE);
            if (currentProfit<moneyRisk) return;
            double lotsToClose = OrderLots()*moneyRisk/currentProfit;
            lotsToClose = MathFloor(lotsToClose/MarketInfo(NULL, MODE_LOTSTEP))*MarketInfo(NULL, MODE_LOTSTEP)+MarketInfo(NULL, MODE_MINLOT);
            Alert("Lots to close: "+DoubleToString(lotsToClose, 2));
            Alert("Win: "+DoubleToString(lotsToClose*pipsProfit*MarketInfo(NULL, MODE_TICKVALUE)/MarketInfo(NULL, MODE_TICKSIZE), 2)+" "+AccountCurrency());
         }
      } 
   }
  }