Create Local Database Cache - Use SQL Server change tracking is disabled

I'm trying to create a new "Local Database Cache" item in Visual Studio 2010 to sync against a local Sql Server Express 2008 R2 database.

When the wizard pops up though开发者_StackOverflow中文版 the "Use SQL Server change tracking" checkbox is disabled. Any ideas? I tried running

ALTER DATABASE MY_Database SET CHANGE_TRACKING = ON

but that had no effect.

Cheers,

Alex..

---

Figured this out..

The database was set to SQL Server 2000 compatibility, set it to SQL Server 2008 and all is good...