runtime 438 with vlookup worksheetfunction

Hello Excel Forum,
I'm writing a macro that populates a list then uses a vlookup to retrieve a value from another worksheet - pretty straightforward. But, I get Runtime error 438 (Ojbect doesn't support this property or method) on the line containing the worksheetfunction. I've typed the "application.worksheetfunction" line into the Immediate window and the expected result was printed. So, I can't figure out why I get the error. Any help will be much appreciated.

Sub testForecastComparison()

    Dim RFSheet As Worksheet
    Dim headerRow As Integer
    Dim rowOffset As Integer
    Dim RFForumla As String, SDRevFormula As String
    Dim cpnPlanbook As Workbook, cpnRPFSheet As Worksheet
    Dim RDCell As Range, FRACell As Range
    
    Set RFSheet = ThisWorkbook.Worksheets("Revenue Forecast Analysis")
    headerRow = 6       'defines where table starts
    rowOffset = 0       'defines next row to fill
    
    Set cpnPlanbook = Workbooks("Accounts Rev tracker Prototype.xlsm")
    Set cpnRPFSheet = cpnPlanbook.Worksheets("Revenue Planner-Forecast")

    For Each RDCell In ThisWorkbook.Worksheets("Revenue Data").Range("Table1").Columns(2).Cells
        If RDCell.Offset(0, 7).value > 0 Or RDCell.Offset(0, 8).value > 0 Then
            rowOffset = rowOffset + 1
            Set FRACell = RFSheet.Range("B" & headerRow + rowOffset)
            FRACell.value = RDCell.value
            FRACell.Offset(0, 1).value = Application.worksheetfuntion.VLookup(RDCell.value, cpnRPFSheet.Range("C:G"), 4, False)
        End If
    Next RDCell

End Sub

Thanks

I've spotted my spelling mistake (no 'c' in worksheetfunction). Apologies to anyone that has taken the time to read this thread...