[VB .NET] How to show help after an OpenFileDialog

my help file (.chm) doesn''t open after an OpenFileDialog.ShowDialog() I open an OpenFileDialog from a first Form to get the path of an Excel file. And if the DialogResult is OK, then I open a second Form. From this second Form, i can''t open my help file. And when i come back on the other Forms I can''t open my help file anymore. There are no problem if I have open my help file before the OpenFileDialog. I use an HelpProvider in each Form and also the command : Help.ShowHelp(Me, helpfile, HelpNavigator.Topic, "fichier.htm") Somebody can help me ?