AutoCAD Inventor :: C# Close File Without Saving?

I am using Inventor 2012 and C#. I would like that, when I close my Form, Inventor and all files that are open will be closed with displaying the message about saving the files .Some  of my opened file are stored in Lists.

This code das not work Inventor still asking me about saving the files.

 private void Form1_FormClosed(object sender, FormClosedEventArgs e)
        {
            if (InventorOpen._started)
            {
                oDrawDoc.Close(false);
                foreach (Inventor.AssemblyDocument openAssemDocument in openAssemDocumentsList)
                {
                    openAssemDocument.Activate();

[code]....