I am attempting to open a pop up form to display a given PDF file using a command button on a subform of the main form. The pop up form opens but with the message "Can't reach this page". I have tried the code in both Open and Load with no success. However when I run the same code from a command button on the pop up form the correct PDF file does open. See the code below. Any ideas?

Private Sub Command2_Click()
Dim filePath As String
filePath = "C:\Users\drbro\OneDrive\Documents\Access\DSM D number scans\" & [Forms]![frmMain]![Child44].[Form]![PDFnum] & ".pdf"

Me.WebBrowser1.Object.Navigate filePath
End Sub

Private Sub Form_Load()
Dim filePath As String
filePath = "C:\Users\drbro\OneDrive\Documents\Access\DSM D number scans\" & [Forms]![frmMain]![Child44].[Form]![PDFnum] & ".pdf"

Me.WebBrowser1.Object.Navigate filePath

End Sub

Private Sub Form_Open(Cancel As Integer)
Dim filePath As String
filePath = "C:\Users\drbro\OneDrive\Documents\Access\DSM D number scans\" & [Forms]![frmMain]![Child44].[Form]![PDFnum] & ".pdf"

Me.WebBrowser1.Object.Navigate filePath

End Sub