LinqToSql ConnectionString won't set to "(None)"

Normally when you click in any whitespace in a LinqToSql dbml file, you can then go over to the properties window and set the Connection to (None). This is essential to me because it allows me to put the connection s开发者_高级运维tring in the web.config.

The "(none)" option does not always show for me, especially after i make updates to the generated classes. Does anyone know why it doesnt sometimes show the none option, and how to make it show it again?

Thanks.

This stopped happening when i upgraded to VS2010-- before that i had to alter manually.