C# sql express 2008 not showing in the list of pre-requisites in setup project

I'm creating an installer via VS setup project, and I'd like to make sure sql express 2008 is installed if it is not already installed.

I right clicked on my installer project and go to Pre-requisites but SQL Server 2008 Express is not there. 2005 is listed, but I need 2008.

I installed SQL Server 2008 Express after Visual Studio. What do I need to do to re-register with Visual Studio so it allo开发者_如何学Pythonws me to select SQL Server 2008 Express?