Have you selected weight changes on the list of friend feed activities you want to share? That option isn't on the weigh-in page, it's on your Friend Feed privacy settings page. To get there, click on the Friend Feed tab under the Community drop-down menu at the top of every page. Then put an X in the Weight change box.
Hope this helps.
"All your life, you have just been waiting for this moment to arise."
(Lennon & McCartney, "Blackbird")
| current weight: 199.0