Unspecified error when pressing F1 key

[KentBurel]

I have a userform that contains a text box that provides information for the first page in my workbook. I want this displayed when the workbook is first opened but only the first time. If the user wants to see the instructions again then he/she can press the F1 key. This all works until the F1 key is pressed and then I get this error message:

Here are my macros that set this up:

The Constants sheet is the first sheet in the workbook. The Constants sheet contains this code:

Option Explicit

Private Sub Worksheet_Deactivate()
    Application.OnKey "{F1}"
    DisplayConstantsHelp.Hide
End Sub
Private Sub Worksheet_Activate()
    Application.OnKey "{F1}", "DisplayConstantsHelp.Show"
End Sub

The ThisWorkBook module contains this code:

Sub Workbook_open()
    DisplayConstantsHelp.Show
End Sub

DisplayConstantsHelp is the name of the userform. I used this technique before to map the F1 key to a userform only when a particular sheet is displayed. Now it's giving me a strange error.

Thanks for your help.

 

[Yongle]

I assume that the userform name is DisplayConstantsHelp

Place code in Sheet Constants code window:

Private Sub Worksheet_Deactivate()
    Application.OnKey "{F1}"
End Sub

Private Sub Worksheet_Activate()
    Application.OnKey "{F1}", "Sheet1.DisplayForm"  ' GREEN = sheet codename,  RED = name of macro
End Sub

Private Sub DisplayForm()
    DisplayConstantsHelp.Show  'BLUE = name of userform
End Sub

 

[KentBurel]

That works! Thank you for your help.