VBA copy paste

Do you see a reason why the goal seeker only fully minimizes the first iteration and not the ones after?

Sub adf()

    Dim iCol        As Long

     Range("b32").Value = 5
    For iCol = 6 To 7
        Range("C31").GoalSeek Goal:=0, ChangingCell:=Range("F36")
        Cells(15, iCol).Value = Range("F36").Value
        Range("b32").Value = Range("b32").Value + 5
    Next iCol
End Sub