Error 400 at a particular line of code in vba? [duplicate]

Question

I have this code:

'Declare variables
Dim wb As Workbook
Dim rv As Range 'rv = row value
Dim wsn As String 'wsn = worksheet name
Dim ws As Worksheet
Dim rws As Worksheet 'record sheet worksheet
Dim ri As Long 'row index used for rv
'Set record workbook and worksheet
Set wb = ActiveWorkbook
Set rws = wb.Worksheets("Record sheet")

'refer to concatenate column
Dim lastr As Long
Dim r As Range
lastr = rws.Cells(Rows.Count, 1).End(xlUp).row
Set r = rws.Range(Cells(2, 7), Cells(lastr, 7))

But when it reaches this code:

Set r = rws.Range(Cells(2, 7), Cells(lastr, 7))

I get a 400 error. I've spent ages trying to figure out whats causing it and i don't know what I'm doing wrong. I've tested my rws variable and it works by going to the correct worksheet when running a "rws.select" test.