Max/Min Value VBA From Column Not Working

Hi,

I'm trying this bit of code to obtain the max and min values and print them into Range C2 and E2, however I get a debug error (Run time error 438, object doesn't support this property or method)

  Dim rng1, rng2 As Range

    Set rng1 = Sheets("Plan").Range("C3:C40")
    Set rng2 = Sheets("Plan").Range("E3:E40")

    Sheets("Plan").Range("C2").Value = Application.WorkheetFunction.Min(rng1)
    Sheets("Plan").Range("E2").Value = Application.WorkheetFunction.Max(rng2)

There must be something wrong with my syntax but I can't figure out what it is! Can somebody help please?

Try,

Sub test()
    Dim rng1 As Range, rng2 As Range
    With ThisWorkbook.Sheets("Plan")    'or delete thisworkbook for the activeworkbook
        Set rng1 = .Range("C3:C40")
        Set rng2 = .Range("E3:E40")
        .Range("C2").Value = Application.Min(rng1)
        .Range("D2").Value = Application.Max(rng2)
    End With
End Sub

or without declaring rng1 and rng2,

Sub test()
    With ThisWorkbook.Sheets("Plan")    'or delete thisworkbook for the activeworkbook
        .Range("C2").Value = Application.Min(.Range("C3:C40"))
        .Range("D2").Value = Application.Max(.Range("E3:E40"))
    End With
End Sub