IsFileOpen function not working correctly

I took most all of the code out so you wouldn't have to go through it. With that code removed it still happens. The first message will say "A file named ...xls aready exists in the in this locations. Do you want to replace it."
Thanks for you help!

Sub PickShift()
    Dim c As Variant
    Dim Dataloc As String
    
CellAddr = ActiveCell.Address

If ActiveCell.Offset(0, 8) = True Then
    ws = Range("L1").Value
    Dim UserID As String
    YourName = InputBox("Enter Your Name:   ", "Welcome ")

    Dim WbSource As Workbook, WbDest As Workbook


    Set WbSource = ThisWorkbook 'book where this code is located
    On Error Resume Next 'enables continued processing if an error occurs
    
        Dataloc = "P:\CUSTSERVICE\Custserv Online Sign Ups\rb\OSM RB BobThuli.xls"

       ' Display a message stating the file in use.
        If IsFileOpen(Dataloc) Then
        MsgBox ("File is currently in use by another user.  Please try again later." _
        & vbNewLine & "If this lasts over 15 minutes contact the I-team.")
        Exit Sub
        End If
    
    
        Workbooks.Open Dataloc, , , , "HotIssue", "HotIssue"
    
'
MsgBox ("Just Tesing")
     Application.ScreenUpdating = True 'Turn back on Screen updating

End If

 ActiveWorkbook.Save
 ActiveWorkbook.Close
 Application.ScreenUpdating = True 'Turn back on Screen updating
 Success = MsgBox("You have successfully picked up this shift.", , "Success")
End Sub

' This function checks to see if a file is open or not. If the file is
' already open, it returns True. If the file is not open, it returns
' False. Otherwise, a run-time error occurs because there is
' some other problem accessing the file.

Function IsFileOpen(filename As String)
    Dim filenum As Integer, errnum As Integer

    On Error Resume Next   ' Turn error checking off.
    filenum = FreeFile()   ' Get a free file number.
    ' Attempt to open the file and lock it.
    Open filename For Input Lock Read As #filenum
    Close filenum          ' Close the file.
    errnum = Err           ' Save the error number that occurred.
    On Error GoTo 0        ' Turn error checking back on.

    ' Check to see which error occurred.
    Select Case errnum

        ' No error occurred.
        ' File is NOT already open by another user.
        Case 0
         IsFileOpen = False

        ' Error number for "Permission Denied."
        ' File is already opened by another user.
        Case 70
            IsFileOpen = True

        ' Another error occurred.
        Case Else
            Error errnum
    End Select

End Function

rjtools

You must read the Forum Rules and in future use Ciode tags when posting VBA to the Forum. I will add them this time.

I can't test this but try changing the code by switching off alerts like this

    On Error Resume Next 'enables continued processing if an error occurs
  Application.DisplayAlerts = False
        'Dataloc = "P:\CUSTSERVICE\Custserv Online Sign Ups\rb\OSM RB BobThuli.xls"
       ' Display a message stating the file in use.
        If IsFileOpen(Dataloc) Then
        MsgBox ("File is currently in use by another user.  Please try again later." _
        & vbNewLine & "If this lasts over 15 minutes contact the I-team.")
        Exit Sub
        End If
    
    
        Workbooks.Open Dataloc, , , , "HotIssue", "HotIssue"
  Application.DisplayAlerts = True