Databound controls inside an INamingContainer control must not be placed inside templated controls such as FormView. See this bug report for an example. Since INamingContainer controls creates their own namespace for their contained controls, two-way databinding using Bind() will not work properly. But when loading the values everything will look fine (because it is done with Eval()) it is not before you try to post back the values that they will mysteriously seem to not land in the database.
This so question demonstrates the issue well: AJAX Tabcontainer inside formview not inserting values
