Indicator period_m1 is not drawn on a backtest with 5 minute choosen as time period

//--------------------------------------------------------------------
// userindicator.mq4 
// The code should be used for educational purpose only.
//--------------------------------------------------------------------
#property indicator_separate_window // Indicator is drawn in the main window
#property indicator_buffers 1       // Number of buffers
#property indicator_color1 Blue     // Color of the 1st line
double Buf_0[];                     // Declaring arrays (for indicator buffers)
//--------------------------------------------------------------------
int init()                          // Special function init()
  {
   SetIndexBuffer(0,Buf_0);         // Assigning an array to a buffer
   SetIndexStyle (0,DRAW_LINE,STYLE_SOLID,2);// Line style
   return;                          // Exit the special funct. init()
  }
//--------------------------------------------------------------------
int start()                         // Special function start()
  {
   int i,                           // Bar index
       Counted_bars;                // Number of counted bars
//--------------------------------------------------------------------
   Counted_bars=IndicatorCounted(); // Number of counted bars
   i=Bars-Counted_bars-1;           // Index of the first uncounted
   while(i>=0)                      // Loop for uncounted bars
     {
   Buf_0[i]=iMomentum(NULL,PERIOD_M1,14,PRICE_CLOSE,0);             // Value of 0 buffer on i bar
      i--;                          // Calculating index of the next bar
     }
//--------------------------------------------------------------------
   return;                          // Exit the special funct. start()
  }
//--------------------------------------------------------------------

I want to draw the momentum using period_m1 when backtesting with 5 minute choosen as time period.

Problem: Momentum period_m1 is only drawn if I backtest with 1 minute choosen as time period.

Has someone an idea how this could work?

Thanks in advance!