Syntax Errors in VBA

I keep getting errors (either else without if or loop without do) in this, and I really have no iea why... can anyone help?! Thanks!

Do Until (Range("I4").Value = 0)

    For i = 2 To lLastrow

                If Range("G" & i).Value = 0 Then
                    i = i + 1

                ElseIf Range("G" & i).Value < 0 Then
                      Do Until (Range("G" & i).Value = 0)
                      For j = 0 To i
                         If Range("F" & i - j).Value < 0 Then
                               Range("F" & i - j).Value = Range("F" & i - j).Value + 1
                              Else: j = j + 1
                              End If
                             Application.Calculate
                        Loop
                    ElseIf Range("G" & i).Value > 0 Then
                        Do Until (Range("G" & i).Value = 0)
                            For k = 0 To i
                             If Range("F" & i - k).Value > 0 Then
                              Range("F" & i - k).Value = Range("F" & i - k).Value - 1
                                   Else: k = k + 1
                                   End If
                               Application.Calculate
                        Loop
                End If


            Application.Calculate
Loop