KERN_PROF help

hi, when trying below code

mib[0] = CTL_KERN;
mib[1] = KERN_PROC;
mib[2] = KERN_PROC_ALL;
mib[3] = 0;
if (sysctl(mib, 3 , NULL, &size, NULL, 0)<0 )
perror(SYSCTL fails);
else
printf("SYSCTL OK\n");

get the error message:
)ENOENT 2) 
"SYSCTL fails: No such file or directory"

what could be the prossible reason?

thanks in advance, 
hm_li2001