Browse Folder Dialog - show msgbox if nothing selected

I'm having some trouble showing a messagebox if the user presses OK but doesn't select a folder using msoFileDialogFolderPicker. Can someone help point me in the right direction?

Sub BrowseFolderDialog()
Dim selectedItem As String

    With Application.FileDialog(msoFileDialogFolderPicker)
        .Title = "Select a Folder"
        .AllowMultiSelect = False
        .InitialFileName = ""
        If .Show = -1 Then
       
         If .SelectedItems.Count > 0 Then
             selectedItem = .SelectedItems(1)
         End If
        
         MsgBox CStr(.SelectedItems(1))
         MsgBox selectedItem 
                
         If Not InStr(selectedItem , ":\") Then
             MsgBox "You didn't select a folder. The procedure has been canceled."
             SaveSettings.OBFilePathDefault = True
             Exit Sub
         End If
        
         
          If .SelectedItems.Count > 0 Then
             selectedItem = .SelectedItems(1)
             SaveSettings.TextBoxCustomPath.Text = selectedItem
             Sheets("Back").Range("J2").Value = selectedItem
          End If
        
        Else
        MsgBox "Canceled"
        
        End If
    End With
End Sub

The 2 MsgBox's I've added show the same string, yet the If Not InStr line returns true regardless if ":\" is in the string or not. Any advice or other methods you can suggest?