title: SQL Compact 4.0 can't open/read sdf file
body: <p>I've installed SQL Compact 4.0 CTP 2 via WPI and used NUPack to add SQLCE.EntityFramework in my project.
  It compiles and run perfectly but I can't open the SDF file in Visual Studio 2010's Server Explorer.</p>
  
  <p>When I try I always receive the following message:</p>
  
  <hr>
  
  <h2>Microsoft Visual Studio</h2>
  
  <h2>This is not a valid SQL Server Compact Database file or this file version is not supported by current SQL Server Compact Engine.</h2>
  
  <h2>OK</h2>
  
  <p>I've already tried to uninstall and reinstall everything.</p>
  
  <p>It cannot be opened in SQL Server 2008 R2 Management Studio also.</p>
  
  <p>Please help!!</p>