Fejl i autogenerering?

Jeg skal have lavet en random kode.. Min Codebehind ser sådan her ud:


Partial Class Default2
    Inherits System.Web.UI.Page
    Protected WithEvents TextBox14 As System.Web.UI.WebControls.TextBox

    Function GeneratePassword(ByVal length As Integer) As String
        'Make sure length and numberOfNonAlphanumericCharacters are valid....
        If ((length < 1) OrElse (length > 128)) Then
            Throw New ArgumentException("Membership_password_length_incorrect")
        End If

        Do While True
            Dim i As Integer
            Dim nonANcount As Integer = 0
            Dim buffer1 As Byte() = New Byte(length - 1) {}

            'chPassword contains the password's characters as it's built up
            Dim chPassword As Char() = New Char(length - 1) {}

            'chPunctionations contains the list of legal non-alphanumeric characters
            Dim chPunctuations As Char() = "!@@$%^^*()_-+=[{]};:>|./?".ToCharArray()

            'Get a cryptographically strong series of bytes
            Dim rng As New System.Security.Cryptography.RNGCryptoServiceProvider
            rng.GetBytes(buffer1)

            For i = 0 To length - 1
                'Convert each byte into its representative character
                Dim rndChr As Integer = (buffer1(i) Mod 87)
                If (rndChr < 10) Then
                    chPassword(i) = Convert.ToChar(Convert.ToUInt16(48 + rndChr))
                Else
                    If (rndChr < 36) Then
                        chPassword(i) = Convert.ToChar(Convert.ToUInt16((65 + rndChr) - 10))
                    Else
                        If (rndChr < 62) Then
                            chPassword(i) = Convert.ToChar(Convert.ToUInt16((97 + rndChr) - 36))
                        Else
                            chPassword(i) = chPunctuations(rndChr - 62)
                            nonANcount += 1
                        End If
                    End If
                End If
            Next

            If nonANcount < 10 Then
                Dim rndNumber As New Random
                For i = 0 To (10 - nonANcount) - 1
                    Dim passwordPos As Integer
                    Do
                        passwordPos = rndNumber.Next(0, length)
                    Loop While Not Char.IsLetterOrDigit(chPassword(passwordPos))
                    chPassword(passwordPos) = chPunctuations(rndNumber.Next(0, chPunctuations.Length))
                Next
            End If

            Return New String(chPassword)
        Loop
    End Function


    Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
        TextBox14.Text = GeneratePassword("10").ToString()
    End Sub
End Class

Men Den kommer med en fejl..

"Objektreferencen er ikke indstillet til en forekomst af et objekt"

I denne linie som bliver markeret med gult:

TextBox14.Text = GeneratePassword("10").ToString()

Hvad er det der er galt??