CreateFile ErrorCode 5

#include  
#include
#include
#include

bool AppendTextToFile(char *filename,char *buf)
{
 HANDLE handle;
 char szbuf[1024]={0};
 strcpy(szbuf,buf);
 handle = CreateFile(filename,FILE_ALL_ACCESS,FILE_SHARE_READ|FILE_SHARE_WRITE|FILE_SHARE_DELETE,NULL,OPEN_ALWAYS,FILE_ATTRIBUTE_NORMAL,NULL);
 if(handle == INVALID_HANDLE_VALUE)
 {
  DWORD i = GetLastError();
  cout<  CloseHandle(handle);
  return false;
 }
 
 DWORD dwNumber;
 SetFilePointer(handle,0,NULL,FILE_END);
 int ilen = strlen(szbuf);
 WriteFile(handle,szbuf,ilen,&dwNumber,NULL);
 CloseHandle(handle);
 return true;
}
void main()
{
 AppendTextToFile("c://test12.txt","123");
}