单片机KEIL出现了different length of parameter lists 的错误，如何修改？

#include

typedef unsigned int u16;

typedef unsigned char u8;

#define GPIO_DIG P0
#define GPIO_KEY P1

u8 KeyValue;

u8 code smgduan[17]={0x3f,0x06,0x5b,0x4f,0x66,0x6d,0x7d,0x07,
0x7f,0x6f,0x77,0x7c,0x39,0x5e,0x79,0x71};//???0~F???

void delay(u16 i)
{
while(i--);
}
void KeyDown(void)

{
char a=0;
GPIO_KEY=0x0f;
if(GPIO_KEY!=0x0f)

加粗处一直在提示错误，如何修改？

delay函数参数不匹配