Closing The Workbook From A Dialog Control

I have a spreadsheet that automatically opens a dialog box when the workbook is opened. This is a little disclaimer intended for other users of the spreadsheet, which if they click ok it simply closes the dialog sheet, but if they click cancel I want it to kick them out of the Workbook without asking them to save changes. I only want it to close that specific workbook incase they have others open that they haven't saved, etc.

The dialog box is opened as follows:

Private Sub Workbook_Open()
DialogSheets("Splash Screen").Show
End Sub

The code I have tried for the closing of the workbook is done by assigning the following macro to the cancel button (note, all but one of the sheets in my workbook is hidden and protected, including the dialog sheet):

Sub Splash_Close()
'
ThisWorkbook.Close SaveChanges:=False
'
'Also tried ActiveWorkbook.Close SaveChanges:=False
'Application.Quit (This closes all excel documents)
'
End Sub

I know there is something I am missing, keeping in mind I am quite experienced with excel, but relatively new to macros and VB programming.

Just a bit extra on this problem. I am creating the file as a template *.xlt, and the error I get when trying to run the example macro I gave at the start is a 1004 error Method close of object _workbook failed.

Also, in an ineresting (baffling for me at the moment) twist is that once you hit end on the error and it just goes to the first page of your spreadsheet, you can then go to ToolsMacros and run the macro from there, and it closes the workbook exactly the way I want it to!