Cause they are not defined. Also, you've forgotten $
sign(I guess, if there is a.noMyKid='noMyKid1'
then sorry):
$sql= "SELECT namaAnak,noSijilLahir
FROM mohon a
INNER JOIN tblstatus_tak_lengkap b on a.noMyKid=b.nomykid
WHERE a.noMyKid='$noMyKid1'";
And to fetch you result set:
while($row = mysql_fetch_assoc($result)){
echo $row['namaAnak'];
echo $row['noSijilLahir'];
}