请教一个关于多单平仓出错的问题，多单在开单价小于开盘价时平仓，总是出错

void OnTick()
  {
     double buyop,buylots; 
     int buydanshu=buydanshu(buyop,buylots);
     if(buydanshu==0 )
      {
        if( Close[0]>High[1] )
          {
           if(selltime!=Time[0])
            {
              if(buy(Lots,0,0,Symbol()+"buy",magic)>0)
                {
                  selltime=Time[0];
                }
            }
          }
      }
     if( Open[
0 ]>buyop)
      {
       closebuy();
      }

  }
void closebuy()
  { 
    double buyop,buylots;
    while(buydanshu(buyop,buylots)>0)
     {
        int t=OrdersTotal();
        for(int i=t-1;i>=0;i--)
         {
           if(OrderSelect(i,SELECT_BY_POS,MODE_TRADES)==true)
             {
               if(OrderSymbol()==Symbol() && OrderType()==OP_BUY && OrderMagicNumber()==magic)
                 {
                   OrderClose(OrderTicket(),OrderLots(),OrderClosePrice(),300,Green);
                 }
             }
         }
        Sleep(800);
     }
  }

int buydanshu(double &op,double &lots)
  {
     int a=0;
     op=0;
     lots=0;
     for(int i=0;i<OrdersTotal();i++)
      {
        if(OrderSelect(i,SELECT_BY_POS,MODE_TRADES)==true)
          {
            if(OrderSymbol()==Symbol() && OrderType()==OP_BUY && OrderMagicNumber()==magic)
              {
                a++;
                op=OrderOpenPrice();
                lots=OrderLots();
              }
          }
      }
    return(a);
  }int buy(double lots,double sl,double tp,string com,int buymagic)
  {
    int a=0;
    bool zhaodan=false;
     for(int i=0;i<OrdersTotal();i++)
      {
        if(OrderSelect(i,SELECT_BY_POS,MODE_TRADES)==true)
          {
            string zhushi=OrderComment();
            int ma=OrderMagicNumber();
            if(OrderSymbol()==Symbol() && OrderType()==OP_BUY && zhushi==com && ma==buymagic)
              {
                zhaodan=true;
                break;
              }
          }
      }
    if(zhaodan==false)
      {
        if(sl!=0 && tp==0)
         {
          a=OrderSend(Symbol(),OP_BUY,lots,Ask,50,Ask-sl*Point,0,com,buymagic,0,White);
         }
        if(sl==0 && tp!=0)
         {
          a=OrderSend(Symbol(),OP_BUY,lots,Ask,50,0,Ask+tp*Point,com,buymagic,0,White);
         }
        if(sl==0 && tp==0)
         {
          a=OrderSend(Symbol(),OP_BUY,lots,Ask,50,0,0,com,buymagic,0,White);
         }
        if(sl!=0 && tp!=0)
         {
          a=OrderSend(Symbol(),OP_BUY,lots,Ask,50,Ask-sl*Point,Ask+tp*Point,com,buymagic,0,White);
         } 
      }
    return(a);
  }