Macro to sum relative column and row

Dim count
ActiveCell.Offset(0, 1).Range("A1").Select

Do
count = count + 1
ActiveCell.Offset(-1, 0).Range("A1").Select



If ActiveCell.Value = "" Then GoTo error1

Loop
error1:
ActiveCell.Offset(0, -2).Select
Selection.End(xlDown).Select
ActiveCell.Offset(1, 1).Range("A1").Select


ActiveCell.FormulaR1C1 = "=SUM(R[-count]C[1]:RC[24])"
ActiveCell.Offset(1, -1).Range("A1").Select


End Sub