为什么启动时无法成功？如何解决？

#include "stdafx.h"
int main(void)
{

HWND cur;
cur=FindWindow("ConsoleWindowClass",NULL);
ShowWindow(cur,SW_SHOWMINIMIZED);
STARTUPINFO StartupInfo;
memset(&StartupInfo,0,sizeof(STARTUPINFO));
StartupInfo.cb=sizeof(STARTUPINFO);
PROCESS_INFORMATION ProcessInformation;

CreateProcess("D:\\Program Files\\Supplicant\\STARSupplicant.exe",NULL,NULL,NULL,FALSE,NORMAL_PRIORITY_CLASS,
NULL,NULL,&StartupInfo,&ProcessInformation);

HWND Sup,Link;
int i=0;
while(TRUE){
Sleep(500);
Sup=FindWindow(NULL,"Supplicant");

Link=FindWindowEx(Sup,0,NULL,"连接");
if(Link==NULL){
i++;
if(i>20){
MessageBox(NULL,"找不到认证程序","错误",MB_OK);
break;
}
}else{

SendMessage(Sup,WM_COMMAND,MAKEWPARAM(IDOK,BN_CLICKED),0);
break;

}
}

return 0;
}
如何判断一个进程的窗口已经出现？