SAPGUI Script in C# not working

Hey guys,

     I'm coding C# to automate some SAPGUI scripting, and I have this wired problem...

      Below is the code piece

               GuiApplication guiApp = (GuiApplication)System.Activator.CreateInstance(Type.GetTypeFromProgID("SapGui.ScriptingCtrl.1"));

                GuiConnection guiConn = guiApp.OpenConnection("MYSYSTEM", true, true);

                GuiSession guiSession = (GuiSession)guiConn.Sessions.Item(0);

                GuiFrameWindow guiWindow = guiSession.ActiveWindow;

                GuiTextField client = (GuiTextField)guiWindow.FindByName("RSYST-MANDT", "GuiTextField");

                GuiTextField login = (GuiTextField)guiWindow.FindByName("RSYST-BNAME", "GuiTextField");

                GuiTextField pass = (GuiTextField)guiWindow.FindByName("RSYST-BCODE", "GuiPasswordField");

                GuiTextField language = (GuiTextField)guiWindow.FindByName("RSYST-LANGU", "GuiTextField");

                client.SetFocus();

                client.Text = "XXX";

                login.SetFocus();

                login.Text = "XXXXXXX";

                pass.SetFocus();

                pass.Text = "XXXXXXX";

                language.SetFocus();

                language.Text = "XX";

This code piece worked 100% fine a week ago, but it's not working now... The problem now is that guiConn.Session contains no items after OpenConnection. I'm coding in Visual Studio 2008, I don't think I did any change to my VS project.

I tried guiConn.Children, it contains no items either.

Please help!!!

Thanks,

Shu