kommunikere med NI usb-6501

Jeg forsøger at kommunikere med ni usb-6501.
Det går fint på min labtop men på en stationær computer hvor jeg skal bruge programmet får jeg følgede fejlmeddelsen :

System.IO.FileLoadException was unhandled
  Message=Mixed mode assembly is built against version 'v2.0.50727' of the runtime and cannot be loaded in the 4.0 runtime without additional configuration information.
  Source=Pyknometer
  StackTrace:
      at Pycnometer.NIvalve.OpenValve(Int32 nbr, Boolean open)
      at Pycnometer.NIvalve.CloseValve(Int32 nbr) in c:\Users\mko\Documents\Visual Studio 2010\Projects\Pyknometer\Pyknometer\NIvalve.cs:line 47
      at Pycnometer.Form_pyk.Form1_Load(Object sender, EventArgs e) in c:\Users\mko\Documents\Visual Studio 2010\Projects\Pyknometer\Pyknometer\Form_pyk.cs:line 60
      at System.Windows.Forms.Form.OnLoad(EventArgs e)
      at System.Windows.Forms.Form.OnCreateControl()
      at System.Windows.Forms.Control.CreateControl(Boolean fIgnoreVisible)
      at System.Windows.Forms.Control.CreateControl()
      at System.Windows.Forms.Control.WmShowWindow(Message& m)
      at System.Windows.Forms.Control.WndProc(Message& m)
      at System.Windows.Forms.ScrollableControl.WndProc(Message& m)
      at System.Windows.Forms.Form.WmShowWindow(Message& m)
      at System.Windows.Forms.Form.WndProc(Message& m)
      at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m)
      at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)
      at System.Windows.Forms.NativeWindow.DebuggableCallback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)
      at System.Windows.Forms.SafeNativeMethods.ShowWindow(HandleRef hWnd, Int32 nCmdShow)
      at System.Windows.Forms.Control.SetVisibleCore(Boolean value)
      at System.Windows.Forms.Form.SetVisibleCore(Boolean value)
      at System.Windows.Forms.Control.set_Visible(Boolean value)
      at System.Windows.Forms.Application.ThreadContext.RunMessageLoopInner(Int32 reason, ApplicationContext context)
      at System.Windows.Forms.Application.ThreadContext.RunMessageLoop(Int32 reason, ApplicationContext context)
      at System.Windows.Forms.Application.Run(Form mainForm)
      at Pycnometer.Program.Main() in c:\Users\mko\Documents\Visual Studio 2010\Projects\Pyknometer\Pyknometer\Program.cs:line 18
      at System.AppDomain._nExecuteAssembly(RuntimeAssembly assembly, String[] args)
      at System.AppDomain.ExecuteAssembly(String assemblyFile, Evidence assemblySecurity, String[] args)
      at Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssembly()
      at System.Threading.ThreadHelper.ThreadStart_Context(Object state)
      at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean ignoreSyncCtx)
      at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
      at System.Threading.ThreadHelper.ThreadStart()
  InnerException:


når jeg kalder en metoden OpenValve(nbr, false), der ligger i NIvalve:

Projekted kan ses på
http://www.mediafire.com/?bdmagri0ef27fm0

NIvalve ses her:

using System;
using System.ComponentModel;
using System.Windows.Forms;
using NationalInstruments.DAQmx;

namespace Pycnometer
{

    public class NIvalve
    {
        bool[] dataArray;

        System.Windows.Forms.CheckBox[] valveON;
        public NIvalve(System.Windows.Forms.CheckBox[] valveON)
        {
            this.valveON = valveON;
            dataArray = new bool[8];
        }

       
        public void OpenValve(int nbr, bool open)
        {
            Cursor.Current = Cursors.WaitCursor;

            dataArray[nbr] = open;

            using (Task digitalWriteTask = new Task())
            {
                digitalWriteTask.DOChannels.CreateChannel("Dev1/Port0/line0:7", "",
                          ChannelLineGrouping.OneChannelForAllLines);
                DigitalSingleChannelWriter writer = new DigitalSingleChannelWriter(digitalWriteTask.Stream);
                writer.WriteSingleSampleMultiLine(true, dataArray);
            }
        }

        public void OpenValve(int nbr)
        {         
            OpenValve(nbr, true);
            valveON[nbr].Checked = true;             
        }

        public void CloseValve(int nbr)
        {
            OpenValve(nbr, false);
            valveON[nbr].Checked = false;           
        }


    }
}

Hvad kan årsagen være?