Returning Workbook/sheet Through Property Is Failing

I made a new class to make other code less redundant, but it isn't functioning. The class has a "workbook" and "worksheet" member, and these can be accessed through properties. The problem is that the properties don't actually seem to return anything, and no data can be accessed through them.

Private mActiveWorkBook As WorkBook
Private mActiveWorkSheet As Worksheet

Property Get wSheet() As Worksheet
wSheet = mActiveWorkSheet
End Property

Property Get wBook() As WorkBook
wBook = mActiveWorkBook
End Property

'Sets active WorkBook
Sub SetActiveWorkBook(ByVal wBook As String)
Set mActiveWorkBook = Workbooks(wBook)
End Sub

'Sets the activeWorksheet in the workbook.
Sub SetActiveWorkSheet(ByVal wSheet As String)
If mActiveWorkBook Is Nothing Then
MsgBox ("Invalid WorkSheet selection - WorkBook not defined")
Return
End If

Set mActiveWorkSheet = mActiveWorkBook.Worksheets(wSheet)
End Sub

This class is used in the macro as such:

Dim uDate As Updater
Set uDate = New Updater

uDate.SetActiveWorkBook ("Book1.xls")
uDate.SetActiveWorkSheet ("TestTab")

'Below Code is not functioning

uDate.wSheet. Range("A1").Value = "foo"
' Expected result - set Cell A1 in sheet testTab = "foo"
' Actual Result - nothing

Dim st As String
st = uDate.wSheet.Range("B5").Value
MsgBox (st)
' Expected results - bring msgBox of values of cell B5, this cell is not empty
' Actual Result - Empty Message box comes up

So - its fairly obvious to me that something is wrong with the properties. The members themselves are not null, I have verified in the debugger that the class members refer to actual sheets/workbooks, but the properties don't like passing anything out and show as "variable not set" in the debugger. How can I get this to work?? It works fine when I do not use the class, like such:

Dim wB As WorkBook
Set wB = Workbooks("Book1.xls")

Dim wS As Worksheet
Set wS = Worksheets("TestTab")

Dim st As String
st = wS.Range("B5").Value
msgBox(st)

But I would like to get the class and properties to work to save clutter elsewhere.