The error you are getting says two things your databases are in compatibility 80 and your application is also old because this problem is fixed for SQL Server 2008 and .NET 3.5. So change to compatibility 100 and rewrite your connection code if your Asp.net application is Asp.net 2.0 because Asp.net 3.5 compiles as 2.0.
Kind regards,
Gift Peddie