Sum Lastrow formula!!

I get an object fail 1004 with that, but thanks anyway. This works just needs a little formatting then good to go, cheers guys.

Sub Sum_Last_Row()

Set Lastrow = Cells(Rows.Count, "C").End(xlUp).Offset(1, 0)
 
Lastrow.FormulaR1C1 = "=SUM(R2C:R[-1]C)"
 
 
 End Sub