I am getting order close error 4051

I am getting order close error 4051

invalid ticket for order close function.

Below is the code that I am using --- can anyone please provide a solution?

Thx

#include <stdlib.mqh>

// External Variables
extern double LotSize = 0.01;
extern double StopLoss = 500;
extern double TakeProfit = 1000;

extern int Slippage = 5;
extern int MagicNumber = 123;

// Global Variables
int BuyTicket;
int SellTicket;

double UsePoint;
int UseSlippage;

//+------------------------------------------------------------------+
//| expert initialization function |
//+------------------------------------------------------------------+
int init()
{
UsePoint = PipPoint(Symbol());
UseSlippage = GetSlippage(Symbol(),Slippage);
}

//+------------------------------------------------------------------+
//| expert deinitialization function |
//+------------------------------------------------------------------+
int deinit()
{
//----

//----
return(0);
}
//+------------------------------------------------------------------+
//| expert start function |
//+------------------------------------------------------------------+
int start()
{
double FastMA = iMA(NULL,0,5,0,0,0,0);
double SlowMA = iMA(NULL,0,200,0,0,0,0);

//To Buy

if(Close[0] > SlowMA && High[1] < High[2] && High[2] < High[3] && High[3] < High[4]
&& Low[1] < Low[2] && Low[2] < Low[3] && Low[3] < Low[4] && BuyTicket == 0)

{
OrderSelect(SellTicket,SELECT_BY_TICKET);

// Close Order
if(OrderCloseTime() == 0 && SellTicket > 0)
{
double CloseLots = OrderLots();
double ClosePrice = Ask;

bool Closed = OrderClose(SellTicket,CloseLots,ClosePrice,UseSlippage,Red);
}

double OpenPrice = Ask;

// Calculate stop loss and take profit
if(StopLoss > 0) double BuyStopLoss = OpenPrice - (StopLoss * UsePoint);
if(TakeProfit > 0) double BuyTakeProfit = OpenPrice + (TakeProfit * UsePoint);

// Open buy Order
BuyTicket = OrderSend(Symbol(),OP_BUY,LotSize,OpenPrice,UseSlippage,
BuyStopLoss,BuyTakeProfit,"Buy Order",MagicNumber,0,Green);

SellTicket = 0;
}

// Sell Order
if(Close[0] < SlowMA && High[1] > High[2] && High[2] > High[3] && High[3] > High[4]
&& Low[1] > Low[2] && Low[2] > Low[3] && Low[3] > Low[4] && SellTicket == 0)
{
OrderSelect(BuyTicket,SELECT_BY_TICKET);
if(OrderCloseTime() == 0 && BuyTicket > 0)

{
CloseLots = OrderLots();
ClosePrice = Bid;

Closed = OrderClose(BuyTicket,CloseLots,ClosePrice,UseSlippage,Red);
}

OpenPrice = Bid;

if(StopLoss > 0) double SellStopLoss = OpenPrice + (StopLoss * UsePoint);
if(TakeProfit > 0) double SellTakeProfit = OpenPrice - (TakeProfit * UsePoint);

SellTicket = OrderSend(Symbol(),OP_SELL,LotSize,OpenPrice,UseSlippage,
SellStopLoss,SellTakeProfit,"Sell Order",MagicNumber,0,Red);

BuyTicket = 0;

}
return(0);
}

//Pip Point Function
double PipPoint(string Currency)
{
int CalcDigits = MarketInfo(Currency,MODE_DIGITS);
if(CalcDigits == 2 || CalcDigits == 3) double CalcPoint = 0.01;
else if(CalcDigits == 4 || CalcDigits == 5) CalcPoint = 0.0001;
return(CalcPoint);
}

// Get Slippage Function
int GetSlippage(string Currency, int SlippagePips)
{
int CalcDigits = MarketInfo(Currency,MODE_DIGITS);
if(CalcDigits == 2 || CalcDigits == 4) double CalcSlippage = SlippagePips;
else if(CalcDigits == 3 || CalcDigits == 5) CalcSlippage = SlippagePips * 10;
return(CalcSlippage);
}