It can take a while for Google Play to send out updates.
Took about 24hrs for my last update then I saw the magic 'Updating' logo and there it was.
Something you can do, uninstall then re-install the older version then wait for Google Play again, should update.
Actually I think my first upload of my app I wasn't getting updates but all of a sudden they got unstuck and started.
Also of course if your version v 1.2 is up there then any new installers will get that version.