The sample code does not work on STM32F103C6 - stm32

Question

experts.
I am new to STM32.
So I downloaded some sample code from github.
https://github.com/yohanes-erwin/stm32f103-keil
And I download the simple led blinking code of it to the STM32F103C6 developing board but it doesn't work at all.
The original program embedded on the chip had been erased successfully ( originally the led was always on and LCD screen shows some text, but now after I download the code, the led is off and screen off. So I think the downloading is successful.) but the code does not work.
When I download the original code to the chip, it works again. So I think the chip isn't broken.
I think it's because of compatibility of sample code and my chip. The sample code was written for STM32F103C8. But it was a very simple code. What is the reason?
Here is the code.
#include "stm32f10x.h"
#include "stm32f10x_rcc.h"
#include "stm32f10x_gpio.h"
void delay(unsigned int nCount);
GPIO_InitTypeDef GPIO_InitStruct;
int main (void)
{
// Enable clock for GPIOA
RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA, ENABLE);
// Configure PA4 as push-pull output
GPIO_InitStruct.GPIO_Pin = GPIO_Pin_4;
GPIO_InitStruct.GPIO_Speed = GPIO_Speed_2MHz;
GPIO_InitStruct.GPIO_Mode = GPIO_Mode_Out_PP;
GPIO_Init(GPIOA, &GPIO_InitStruct);
while (1)
{
/* Toggle LED on PA0 */
// Reset bit will turn on LED (because the logic is interved)
GPIO_ResetBits(GPIOA, GPIO_Pin_4);
delay(1000);
// Set bit will turn off LED (because the logic is interved)
GPIO_SetBits(GPIOA, GPIO_Pin_4);
delay(1000);
}
}
// Delay function
void delay(unsigned int nCount)
{
unsigned int i, j;
for (i = 0; i < nCount; i++)
for (j = 0; j < 0x2AFF; j++);
}