Keil直接显示target not created 是什么问题?附单片机程序

#include <reg52.h>
#define uchar unsigned char
#define uint unsigned int
sbit S1=P3^0;
sbit flag=P3^7;//???ж?????????     
void delay(uint z)
{
uint x,y;
for(x = z; x > 0; x--)
  for(y = 114; y > 0 ; y--);   
}
//?ж?????
void int1Init()
{
EA = 1;//?????ж?
EX1 = 1;//?????ж?1
IT = 1;//???ж?1????????
}
void int1() interrupt 2
{
P1=~P1;
}
void main()
{
int1Init();
while (1)
{
  if(S1==0)
  {
   delay(20);//????????
   if (S1==0)
   {
    flag=1;
    flag=0;
   ?? while (S1==0);//??????
   }
  }
}
}