Executing Package using C#: returns failure

Hi,

I have a WPF application that kicks start a package execution on a button click handler. I was using VS2010 & .Net Framework 3.5 in previous release of our product and this feature works well there. But Now I'm using VS2013 DTS tool for creating my SSIS packages & application is using .Net 4.0 framework, the same code doesn't work properly. Execute Method returns failure. No clue how to proceed further. any suggestions please..

Thanks in Advance,

 string pkgLocation;
      Package pkg;
      Application app;
      DTSExecResult pkgResults;

      pkgLocation =
        @"C:\Program Files\Microsoft SQL Server\100\Samples\Integration Services" +
        @"\Package Samples\CalculatedColumns Sample\CalculatedColumns\CalculatedColumns.dtsx";
      app = new Application();
      pkg = app.LoadPackage(pkgLocation, null);
      pkgResults = pkg.Execute();