求大神看一下我的代码段哪里错了？

Public Class Form1
Dim a() As Integer = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10}
Dim b() As Integer = {4, 7, 9, 10}, c(5) As Integer
Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
Dim i As Integer
For i = 0 To UBound(a)
TextBox1.Text &= a(i) & vbTab
Next
For i = 0 To UBound(b)
TextBox2.Text &= b(i) & vbTab
Next
End Sub
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Dim i, j, flag, k As Integer
k = 0
For i = 0 To UBound(a)
flag = 1
For j = 0 To UBound(b)
If b(j) = a(i) Then
flag = 0
Exit For
End If
Next
If flag = 1 Then
c(k) = a(i)
k = k + 1
End If
Next
For i = 0 To k - 1
TextBox3.Text &= c(i) & vbTab
Next
End Sub
End Class
按照老师教的写的，可是总是运行不起来