STM8L151G3 TIM4 not working

[zin10]

MCU: STM8L151G3U6
ISSUE: TIM4 interrupt doesnt seem working 
Connections:
                 1. LED on pin PB0
                 2. Push button/ switch on pin PC5

Scenario:
1. User press the push button

2. Toggles the LED

Observation:
Without using the TIM4 interrupt, the code works perfectly fine, when the TIM4 is used, the excutions reaches the first wait_50ms(); (red colour) and never go beyond this line, I would appreciate if any one would address the issue. BTW: I have used IRQHandler, 23  also but same result.

/===== Header files ======

#include "stm8l15x.h"

// Software timing counters

volatile uint16_t tick_1ms = 0;

volatile uint8_t flag_50ms = 0;

volatile uint8_t flag_100ms = 0;

volatile uint8_t flag_1min = 0;

volatile uint16_t soft_50ms = 0;

volatile uint16_t soft_100ms = 0;

volatile uint16_t soft_1min = 0;

//==== System Clock Configuration =====

void CLK_Config(void)

{

    CLK_DeInit(); // Reset the clock to its default setting

    CLK_HSICmd(ENABLE);// Enable the internal clock speec osscilator ( HSI = 16 MHz)

    while(CLK_GetFlagStatus(CLK_FLAG_HSIRDY) == RESET);// Wait until HSI is ready and stable

    CLK_SYSCLKSourceConfig(CLK_SYSCLKSource_HSI);// Set HSI as a system clock source

    CLK_SYSCLKDivConfig(CLK_SYSCLKDiv_1); // Set system clock prescaler: devide by 1(full 16 MHz)

}

void TIM4_Config(void)

{

    TIM4_DeInit();

    TIM4_TimeBaseInit(TIM4_Prescaler_128, 125); // 16MHz / 128 = 125kHz; 125 -> 1ms

    TIM4_ClearFlag(TIM4_FLAG_Update);

    TIM4_ITConfig(TIM4_IT_Update, ENABLE);

    TIM4_Cmd(ENABLE);

}

INTERRUPT_HANDLER(TIM4_UPD_OVF_TRG_IRQHandler, 25)

{

    TIM4_ClearITPendingBit(TIM4_IT_Update);

    tick_1ms++;

    if (++soft_50ms >= 50) {

        soft_50ms = 0;

        flag_50ms = 1;

    }

    if (++soft_100ms >= 100) {

        soft_100ms = 0;

        flag_100ms = 1;

    }

    if (++soft_1min >= 60000) {

        soft_1min = 0;

        flag_1min = 1;

    }

//TIM4_ClearITPendingBit(TIM4_IT_Update);

}

// Utility: wait for 50ms debounce

void wait_50ms(void)

{

    flag_50ms = 0;

    while (!flag_50ms);

}

void wait_100ms(void)

{

    flag_100ms = 0;

    while (!flag_100ms);

}

//==== Main Function =====

int main()

{

     uint8_t system_on = 0;          // 0 = off, 1 = on

    GPIO_Init(GPIOC, GPIO_Pin_5, GPIO_Mode_In_PU_No_IT); // Initialize Buttons Input

    GPIO_Init(GPIOB, GPIO_Pin_0, GPIO_Mode_Out_PP_Low_Fast); // Initialize LEDS

    CLK_Config();        // System clock

    TIM4_Config();

    enableInterrupts();

    while(1)

    {

        if(GPIO_ReadInputDataBit(GPIOC, GPIO_Pin_5) == RESET)

        {

            wait_50ms();

            if(system_on == 0)

            {

                // Turn on system

                 system_on = 1;

                 GPIO_SetBits(GPIOB, GPIO_Pin_0);

                 // Blink twice

                  GPIO_ToggleBits(GPIOB, GPIO_Pin_0);

                  wait_100ms();

                  GPIO_ToggleBits(GPIOB, GPIO_Pin_0);

                  wait_100ms();

              }

             else

             {

                   // Turn off system

                  system_on = 0;

                 GPIO_ResetBits(GPIOB, GPIO_Pin_0);

              }

              while(GPIO_ReadInputDataBit(GPIOC, GPIO_Pin_5) == RESET)

              wait_50ms();

        }
   }
}