low power modes

[meena]

this part in my code completely making my prototype to sleep which should not.As my standby should workout if the main power supply is OFF for 30 seconds.

I have tried shutdown mode and exti thats too behaved the same

Please help what may be wrong

   __HAL_RCC_PWR_CLK_ENABLE();
    /* Check if the system was resumed from Standby mode */
    if (__HAL_PWR_GET_FLAG(PWR_FLAG_SB) != RESET)
    {
      /* Clear Standby flag */
      __HAL_PWR_CLEAR_FLAG(PWR_FLAG_SB);
      /* Check and Clear the Wakeup flag */
      if (__HAL_PWR_GET_FLAG(PWR_FLAG_WUF4) != RESET)
      {
        __HAL_PWR_CLEAR_FLAG(PWR_FLAG_WUF4);
      }
    }

    HAL_Delay(30000);
    

    HAL_PWR_EnableWakeUpPin(PWR_WAKEUP_PIN4_HIGH);

    HAL_PWR_EnterSTANDBYMode();