Adding Database reference:
http://blogs.msdn.com/b/gertd/archive/2009/06/10/system-objects-in-tempdb.aspx
Simple Solution
The problem is the master.dbscema is not referenced by default (I can only assume because it doesn't make any assumptions about your database setup). So what you need to do is add it:
Open the database project.
- Select the "References" folder and right-click select "Add Database Reference".
- Add the reference to "C:\Program Files (x86)\Microsoft Visual Studio 9.0\VSTSDB\Extensions\SqlServer\2008\DBSchemas\master.dbschema".
- all the warnings disappear.