From Visual Studio 2010 win7, to Visual studio 2013 win 8.1 - System.AccessViolationException

We are using the current project to help with our scanning needs:

http://www.codeproject.com/Articles/171666/Twain-for-WPF-Applications-Look-Ma-No-Handles

This works correctly in 2010 with Win7

We are wanting to move onto win 8.1 with Visual Studio 2013. Pleas help us resolve why the following error is happening:

The native api call is:

        [DllImport("twain_32.dll", EntryPoint = "#1")]
        public static extern TwainResult DsmIdentity([In, Out] Identity origin, IntPtr zeroPtr, DataGroup dg, DataArgumentType dat, Message msg, [In, Out] Identity idds);

An unhandled exception of type 'System.AccessViolationException' occurred in TwainDotNet.dll

Watson