Message Box Help Button

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The Code

MessageBox.Show("No Room selected", _
"Data Entry Error", MessageBoxButtons.RetryCancel, _
MessageBoxIcon.Exclamation, _
MessageBoxDefaultButton.Button1, _
0, "Ch12ProjHelp.chm", _
HelpNavigator.KeywordIndex, "Library Room")

opens the chm file but opens the first item in the TOC instead of the
requested item in the Index. What do I need to do to get it to open the
Index item requested.