What am I doing wrong?

I want to enable a "help" form when a user presses F1.

My Code:

Code:
Private Sub frmMain_KeyDown(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyEventArgs) Handles MyBase.KeyDown
        Dim HelpForm As New frmHelp()
        If e.KeyCode = Keys.F1 Then
            HelpForm.ShowDialog()
        End If
    End Sub
What happens is if a user hits F1 then the form will show... BUT if the user hits [x] (form is closed) and you return to the main form and hit F1 - nothing happens...??

Thanks..

Anjari