ActiveDocument.BeginSave Event Does Not Occur in IJCAD

private void button_Click (object sender, EventArgse)
{ 
    app = new GcadApplication();
    app.Visible=true;
    app.ActiveDocument.BeginSave+=new_DGcadDocumentEvents_BeginSaveEventHandler(this.Save);
}

private void save (string fileName) 
{
    // event processing
    // (omitted)
}