DWT in STM32f103RB

I tried to impement simple delay function using DWT block in stm32f103rb it looks like this

''' /* Use DWT_Delay_Init (); and DWT_Delay_us (microseconds) in the main */

__STATIC_INLINE void DWT_Delay_us(volatile uint32_t microseconds)
{
  volatile uint32_t clk_cycle_start = DWT->CYCCNT;

  /* Go to number of cycles for system */
  microseconds *= ((SYSCLK_FREQ_72) / 1000000);

  /* Delay till end */
  while ((DWT->CYCCNT - clk_cycle_start) < microseconds);
}



uint32_t DWT_Delay_Init(void) {
  /* Disable TRC */
  CoreDebug->DEMCR &= ~CoreDebug_DEMCR_TRCENA_Msk; // ~0x01000000;
  /* Enable TRC */
  CoreDebug->DEMCR |=  CoreDebug_DEMCR_TRCENA_Msk; // 0x01000000;

  /* Disable clock cycle counter */
  DWT->CTRL &= ~DWT_CTRL_CYCCNTENA_Msk; //~0x00000001;
  /* Enable  clock cycle counter */
  DWT->CTRL |=  DWT_CTRL_CYCCNTENA_Msk; //0x00000001;

  /* Reset the clock cycle counter value */
  DWT->CYCCNT = 0;

     /* 3 NO OPERATION instructions */
  __ASM volatile ("NOP");
  __ASM volatile ("NOP");
  __ASM volatile ("NOP");

  /* Check if clock cycle counter has started */
     if(DWT->CYCCNT)
     {
       return 0; /*clock cycle counter started*/
     }
     else
  {
    return 1; /*clock cycle counter not started*/
  }
}'''

And it does not work! Can you help me what is wrong?