setting variable as a found value produces "compile error" in vba - excel

Question

I'm trying to set a variable based on the value I find, however VB produces "Compile error: invalid identifier", and highlights my variables. I will post code below and identify the line where the error is being produced.
What the code does:
a) Asks user to input start & end dates in the format week/year
b) If the user does that the code will find the specified value in the range and take the value which is 4 rows below that value.
That's it - pretty simple & straightforward...
Private Sub Workbook_Open()
Dim ans As Variant, stDt As Variant, endDt As Variant, endCl As Variant, stCl As Variant, wsheet As Worksheet, wbook As Workbook, _
fn_stDt As Variant, wk As Integer, rl_st_Dt As String, rl_end_Dt As String, fn_endDt As Variant
Set wbook = Workbooks("wbook1.xlsm")
Set wsheet = wbook.Worksheets("sheet1")
ans = MsgBox("Would you like to specify the range of dates now?", vbYesNo, "Select answer")
If ans = vbYes Then
stDt = Application.InputBox("Please input the starting date", "Start week for forecast / sales", "ww/yyyy", vbOKCancel, vbQuestion)
If stCl = vbCancel Then
Exit Sub
End If
endDt = Application.InputBox("Please input the end date", "End week for forecast / sales", "ww/yyyy", vbOKCancel, vbQuestion)
If endCl = vbCancel Then
Exit Sub
End If
Else
Exit Sub
End If
With wsheet.Range("S5", Range("S5").End(xlToRight))
Set fn_stDt = .Find(what:=stDt, LookIn:=xlValues, searchorder:=xlByRows, _
searchdirection:=xlNext, MatchCase:=False, searchformat:=False)
If Not fn_stDt Is Nothing Then
wk = fn_stDt.Offset(-2, 0).Value
If wk.Value <> wk.Offset(0, 1).Value Then 'Compile Error: Invalid qualifier error appears first here and highlights "wk"
rl_st_Dt.Value = wk.Offset(-4, 0).Value
ElseIf wk.Value = wk.Offset(0, 1) Then
rl_st_Dt.Value = wk.Offset(-4, 1).Value
End If
End If
End With
With wsheet.Range("S5", Range("S5").End(xlToRight))
Set fn_endDt = .Find(what:=endDt, LookIn:=xlValues, searchorder:=xlByRows, _
searchdirection:=xlNext, MatchCase:=False, searchformat:=False)
If Not fn_endDt Is Nothing Then
wk.Value = fn_endDt.Offset(-2, 0).Value
If wk.Value <> wk.Offset(0, 1).Value Then
rl_end_Dt.Value = wk.Offset(-4, 0).Value
ElseIf wk.Value = wk.Offset(0, 1).Value Then
rl_end_Dt.Value = wk.Offset(-4, 1).Value
End If
End If
End With
End Sub
Could anyone please propose a resolution to the above?
Thanks