Can a dll created in Visual Web Dev 2010 Express be used in Visual Studio 2008 - dll in not a microsoft.net module

Hi all,

I created a dll in Visual Web Developer 2010 Express and it works there but when I copied the dll to a project in Visual Studio 2008 I got the error message

DllName.dll in not a microsoft.net module

I'm assuming that the dll is not backwards compatible.  Is it possible to create the dll in Visual Web Devloper 2010 Express and target earlier versions?

Note:

Visual Web Developer 2010 Express - .NET 4.5

Visual Studio 2008 - .NET 3.5

Thanks