event handling function not found CheckEntryBollingerBands.mq5

[Sphelele Sphesihle Lubanyana]

string CheckEntry()
   {
   // create an array for prices
   MqlRates PriceInfo[];
   
   // sort the price Array from the current candle downwards
   ArraySetAsSeries(PriceInfo, true);
   
   // we fill the array with the pricedata
   //int Data = CopyRates(Symbol(), Period(), 0, Bars (Symbol(), Period()), PriceInfo);
   int Data = CopyRates(Symbol(), Period(), 0, 3, PriceInfo);
   
   // create a string variable for signal
   string Signal = "";
   
   // create an Array for several prices
   double middleBandArray[];
   double upperBandArray[];
   double lowerBandArray[];
   
   //Sort the price array from the current candle downwards;
   ArraySetAsSeries(middleBandArray, true);
   ArraySetAsSeries(upperBandArray, true);
   ArraySetAsSeries(lowerBandArray, true);
   
    //define Bollinger Bands
  double bollingerBandsDefination= iBands(_Symbol,_Period, 34, 0, 2.100, PRICE_CLOSE);
  
  //Price infor int the errays
  CopyBuffer(bollingerBandsDefination,0, 0, 3, middleBandArray);
  CopyBuffer(bollingerBandsDefination,1, 0, 3, upperBandArray);
  CopyBuffer(bollingerBandsDefination,2, 0, 3, lowerBandArray);
  
  //calc ea fore the last candle
  double myMiddleValue0 = middleBandArray[0];
  double myUpperValue0 = upperBandArray[0];
  double myLowerValue0 = lowerBandArray[0];
  
  //calc ea fore the current candle
  double myMiddleValue1 = middleBandArray[1];
  double myUpperValue1 = upperBandArray[1];
  double myLowerValue1 = lowerBandArray[1];
  
  // buy signal
  if ((PriceInfo[1].close < myLowerValue1) && (PriceInfo[0].close > myLowerValue0))
  Signal = "Buy";
    // Sell signal
  if ((PriceInfo[1].close > myUpperValue1) && (PriceInfo[0].close < myUpperValue0))
  Signal = "Sell";
   
  
   return Signal;
   }