HELLO.........MY GRANDAUGHTER IS 18 MONTHS OLD AND DOESN'T TALK. SHE

HELLO.........MY GRANDAUGHTER IS 18 MONTHS OLD AND DOESN'T TALK. SHE SAYS.."UNK" FOR WATER AND HAS NO OTHER WORDS....NOT EVEN MOMMY. SHE LIVES WITH ME AND I SPEND ALL DAY TEACHING HER EVERYTHING I DID FOR MY OWN CHILDREN. I READ TO HER, SHOW HER PICTURES AND TAKE HER EVERY PLACE I GO. I SPEND ALL DAY EXPLAINING ALL THAT WE HAVE DONE. BUT SHE LOOKS AT ME AND SAYS NOTHING. THE DOCTOR SAID HER HEARING IS FINE. SHE UNDERSTANDS ME WHEN I TELL HER TO DO SOMETHING. WHAT COULD BE WRONG?