please some one should help check this indicator that does not display

[fe98lix]

I have this indicator code but it does not display any data on chart (in form of histograms).  please some one should check it out for me

#property indicator_separate_window
#property indicator_levelcolor DimGray
#property indicator_buffers 2
#property indicator_color1 Green
#property indicator_color2 Red
#property indicator_level1 25.0
#property indicator_level2 15.0

extern int Len = 150;
extern int HistoryBars = 500;
extern int TF1 = 0;
extern int TF2 = 0;
extern bool ModeHL = TRUE;
extern bool ModeOnline = TRUE;
extern bool ModeinFile = FALSE;
extern bool ModeHistory = FALSE;
extern bool alert = FALSE;
extern bool sound = FALSE;
extern bool email = FALSE;
extern bool GV = FALSE;
extern double UrovenSignal = 25.0;

double BuySignalBuffer[];
double SellSignalBuffer[];

void CalculateSignals()
{
   int historyBars = HistoryBars / (TF2 * 3);
   ArrayResize(BuySignalBuffer, historyBars);
   ArrayResize(SellSignalBuffer, historyBars);

   for (int i = historyBars; i >= 0; i--)
   {
      int shift = iBarShift(NULL, TF2, iTime(NULL, TF2, i));
      double buySignal = 0.0;
      double sellSignal = 0.0;

      for (int j = shift; j >= shift - TF2; j--)
      {
         double closePrice = iClose(NULL, TF1, j);
         double highPrice = ModeHL ? iHigh(NULL, TF1, j) : MathMax(iOpen(NULL, TF1, j), closePrice);
         double lowPrice = ModeHL ? iLow(NULL, TF1, j) : MathMin(iOpen(NULL, TF1, j), closePrice);

         if (highPrice > buySignal)
            buySignal = highPrice;

         if (lowPrice < sellSignal || sellSignal == 0.0)
            sellSignal = lowPrice;
      }

      if (buySignal > 0.0 && sellSignal > 0.0)
      {
         int index = historyBars - i;
         BuySignalBuffer[index] = buySignal;
         SellSignalBuffer[index] = sellSignal;
      }
   }
}

int init()
{
   SetIndexBuffer(0, BuySignalBuffer, INDICATOR_DATA);
   SetIndexBuffer(1, SellSignalBuffer, INDICATOR_DATA);

   SetIndexStyle(0, DRAW_LINE);
   SetIndexStyle(1, DRAW_LINE);

   SetIndexLabel(0, "Buy");
   SetIndexLabel(1, "Sell");

   SetIndexDrawBegin(0, Len);
   SetIndexDrawBegin(1, Len);

   if (ModeinFile || ModeHistory)
   {
      CalculateSignals();
   }

   return 0;
}

int start()
{
   if (ModeOnline)
   {
      CalculateSignals();
   }

   int limit = MathMin(Bars - Len, HistoryBars / (Period() / TF2));

   for (int currentBar = limit; currentBar >= 0; currentBar--)
   {
      if (BuySignalBuffer[currentBar] > UrovenSignal && BuySignalBuffer[currentBar] < 1000000.0)
      {
         if (alert)
            Alert("Buy Signal");

         if (sound)
            PlaySound("alert.wav");

         if (email)
            SendMail("Buy Signal", "Buy Signal received");

         if (GV)
            GlobalVariableSet(Symbol() + "-SP-" + Period(), 1);
      }

      if (SellSignalBuffer[currentBar] > UrovenSignal && SellSignalBuffer[currentBar] < 1000000.0)
      {
         if (alert)
            Alert("Sell Signal");

         if (sound)
            PlaySound("alert.wav");

         if (email)
            SendMail("Sell Signal", "Sell Signal received");

         if (GV)
            GlobalVariableSet(Symbol() + "-SP-" + Period(), -1);
      }
   }

   return 0;
}

[William Roeder]

fe98lix: I have this indicator code but it does not display any data on chart (in form of histograms).

#property indicator_levelcolor DimGray
#property indicator_buffers 2
#property indicator_color1 Green
#property indicator_color2 Red
#property indicator_level1 25.0
#property indicator_level2 15.0

Where do you set that you want histograms? Program Properties (#property) - Preprocessor - Language Basics - MQL4 Reference