Не могу найти решение ошибки

Private Sub k2_Click()
Dim t As Single, n As Integer, i As Integer, a As Single, a1 As Single, _
    an As Single, ah As Single
 a1 = InputBox("a0", "Ввод", 1.3)
 ah = InputBox("ah", "Ввод", 0.1)
 an = InputBox("an", "Ввод", 2.5)
 n = (an - a1) / ah
    With Gr
        Dim p = Open("result.txt") For Output As #1 
  .Text = "    N     A[м]    T[c] "
        For i = 0 To n
            a = a1 + i * ah
            Call integral(a, b, eps, t)
            t = D ^ 2 * t / (fi * Sqr(2 * g))
            .Text = .Text + vbCrLf + Format(i, "  00") + Format(a, "     0.0") +
                    Format(t, "     000.0000")
        Next i
        Print("#1, .Text")
        Close("#1")
    End With
End Sub

VERSION 5.00
Begin VB.Form form1 
   Caption         =   "Информатика курсовая работа"
   ClientHeight    =   5250
   ClientLeft      =   3570
   ClientTop       =   1200
   ClientWidth     =   5070
   LinkTopic       =   "Форма1"
   ScaleHeight     =   5250
   ScaleWidth      =   5070
   Begin VB.TextBox Gr 
      BeginProperty Font 
         Name            =   "Courier New"
         Size            =   9.75
         Charset         =   204
         Weight          =   400
         Underline       =   0   'False
         Italic          =   0   'False
         Strikethrough   =   0   'False
      EndProperty
      Height          =   5175
      Left            =   0
      MultiLine       =   -1  'True
      TabIndex        =   0
      Top             =   0
      Width           =   5055
   End
   Begin VB.Menu k1 
      Caption         =   "Данные"
   End
   Begin VB.Menu k2 
      Caption         =   "Расчет"
      Enabled         =   0   'False
   End
   Begin VB.Menu k3 
      Caption         =   "О работе"
   End
   Begin VB.Menu k4 
      Caption         =   "Выход"
   End
End
Attribute VB_Name = "form1"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = True
Attribute VB_Exposed = False
Option Explicit
Dim D As Single, d1 As Single, d2 As Single, h As Single, h1 As Single, h2 As Single, b As Single, fi As Single, eps As Single, g As Single
 
Private Sub k1_Click()
 b = InputBox("Начальный уровень воды", "Ввод", 3)
 D = InputBox("Диаметр резервуара", "Ввод", 1.8)
 d1 = InputBox("Диаметр", "Первое отверстие", 0.05)
 h1 = InputBox("Высота", "Первое отверстие", 1.2)
 d2 = InputBox("Диаметр", "Второе отверстие", 0.01)
 h2 = InputBox("Высота", "Второе отверстие", 0.6)
 fi = InputBox("Коэффициент истечения", "Ввод", 0.61)
 g = InputBox("Ускорение силы тяжести", "Ввод", 9.81)
 eps = InputBox("Точность вычислений интеграла", "Ввод", 0.0001)
 k2.Enabled = True
End Sub
 
Private Sub k2_Click()
Dim t As Single, n As Integer, i As Integer, a As Single, a1 As Single, _
    an As Single, ah As Single
 a1 = InputBox("a0", "Ввод", 1.3)
 ah = InputBox("ah", "Ввод", 0.1)
 an = InputBox("an", "Ввод", 2.5)
 n = (an - a1) / ah
 With Gr
  Open "result.txt" For Output As #1
  .Text = "    N     A[м]    T[c] "
  For i = 0 To n
    a = a1 + i * ah
    Call integral(a, b, eps, t)
    t = D ^ 2 * t / (fi * Sqr(2 * g))
    .Text = .Text + vbCrLf + Format(i, "  00") + Format(a, "     0.0") + _
            Format(t, "     000.0000")
  Next i
  Print #1, .Text
  Close #1
 End With
End Sub
 
Private Sub k3_Click()
   MsgBox ("Курсовая работа по информатике.")
End Sub
 
Private Sub k4_Click()
  End
End Sub
 
Private Function f(x As Single) As Single
 f = (1 / (d1 ^ 2 * Sqr(x - h1) + d2 ^ 2 * Sqr(x - h2)))
End Function
 
Private Sub integral(a As Single, b As Single, eps As Single, s As Single)
  Dim n As Integer, i As Integer, h As Single, x As Single, s0 As Single
  n = 2
  s = 0
  Do
    n = n * 2
    s0 = s
    h = (b - a) / n
    x = a
    s = f(a) + f(b)
    For i = 1 To n - 1 Step 2
     x = a + i * h
     s = s + 4 * f(x)
     If i < n - 1 Then x = x + h: s = s + 2 * f(x)
    Next i
    s = h * s / 3
  Loop While Abs(s0 - s) / 15 > eps
End Sub