Barras de histograma não aparece no indicador criado! Alguém me ajuda ?

[Augusto Sales]

//+------------------------------------------------------------------+

//|                                                         ind2.mq5 |

//|                        Copyright 2020, MetaQuotes Software Corp. |

//|                                             https://www.mql5.com |

//+------------------------------------------------------------------+

#property copyright "Copyright 2020, MetaQuotes Software Corp."

#property link      "https://www.mql5.com"

#property version   "1.00"

#property indicator_separate_window

#property indicator_buffers 1

#property indicator_plots   1

//--- plot Volume

#property indicator_label1  "Volume"

#property indicator_type1   DRAW_LINE

#property indicator_color1  clrRed

#property indicator_style1  STYLE_SOLID

#property indicator_width1  4

//--- indicator buffers

double         VolumeBuffer[];

//+------------------------------------------------------------------+

//| Custom indicator initialization function                         |

//+------------------------------------------------------------------+

int OnInit()

  {

//--- indicator buffers mapping

   SetIndexBuffer(0,VolumeBuffer,INDICATOR_DATA);

   //IndicatorSetString(INDICATOR_SHORTNAME, "Volume");

//---

   return(INIT_SUCCEEDED);

  }

//+------------------------------------------------------------------+

//| Custom indicator iteration function                              |

//+------------------------------------------------------------------+

int OnCalculate(const int rates_total,

                const int prev_calculated,

                const datetime &time[],

                const double &open[],

                const double &high[],

                const double &low[],

                const double &close[],

                const long &tick_volume[],

                const long &volume[],

                const int &spread[])

  {

   

   if(prev_calculated == 0){

      for(int index = 0; index < rates_total; index++){

         VolumeBuffer[index] = (double)volume[index];

      }

   }else{

      VolumeBuffer[rates_total - 1] = (double)volume[rates_total - 1];

   }

   

   return(rates_total);

  }

//+------------------------------------------------------------------+