Text Appension, what am I doing wrong?

[MiserableMad]

NM got it...is this good for SIMPLE text encryption?

#Region "Encrypt/Decrypt"
    Private Sub btnSimpleEncrypt_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnSimpleEncrypt.Click
        Dim current As String
        Dim intCurrSTR As Integer
        Dim random As New Random
        rndnum = random.Next(100, 399)
        counter = 1
        txt2.Text = ""
        setASC()
        If validatePSW() = False Then
            MsgBox("Password error", , Me.Text)
            Exit Sub
        End If

        Dim pswName As String
        pswName = one.Text & two.Text & three.Text & four.Text & five.Text & six.Text

        Dim changeChar, changeTextAPP As String
        changeTextAPP = pswName & txt1.Text

        For Each character As Char In changeTextAPP
            changeChar &= changecurrent(character)
        Next



        For Each character As Char In changeChar

            intCurrSTR = Asc(character)
            current = Str(intCurrSTR) + setnum() + rndnum
            txt2.Text &= current

        Next

        txt2.Text = rndnum.ToString & txt2.Text


    End Sub

    Private Sub btnSimpleDecrypt_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnSimpleDecrypt.Click
        counter = 1
        If validatePSW() = False Then
            MsgBox("Password error", , Me.Text)
            Exit Sub
        End If
        setASC()

        On Error Resume Next
        Dim current, change, changed, final, rdnNum As String
        Dim intCurrSTR, countPlace, intRndNum As Integer
        txt2.Text = String.Empty

        rdnNum = txt1.Text.Substring(0, 3)
        txt1.Text = txt1.Text.Remove(0, 3)



        For countPlace = 0 To txt1.Text.Length Step 3
            change = txt1.Text.Substring(countPlace, 3)
            intCurrSTR = Val(change)
            current = Str(intCurrSTR) - setnum() - Val(rdnNum)
            final &= Chr(current)
        Next

        For Each character As Char In final
            txt2.Text &= changecurrent(character)
        Next

        Dim getchar, currPSW As String
        currPSW = one.Text & two.Text & three.Text & four.Text & five.Text & six.Text
        getchar = txt2.Text.Substring(0, 6)
        If getchar <> currPSW Then
            txt2.Text = ""
        Else
            txt2.Text = txt2.Text.Remove(0, 6)
        End If
        txt1.Text = rdnNum & txt1.Text
    End Sub

    Function validatePSW() As Boolean
        validatePSW = True
        If Not (one.Text.ToLower >= "a" Or one.Text >= "0") Then Return False
        If Not (two.Text.ToLower >= "a" Or two.Text >= "0") Then Return False
        If Not (three.Text.ToLower >= "a" Or three.Text >= "0") Then Return False
        If Not (four.Text.ToLower >= "a" Or four.Text >= "0") Then Return False
        If Not (five.Text.ToLower >= "a" Or five.Text >= "0") Then Return False
        If Not (six.Text.ToLower >= "a" Or six.Text >= "0") Then Return False

    End Function

    Sub setASC()
        intone = Asc(one.Text)
        inttwo = Asc(two.Text)
        intthree = Asc(three.Text)
        intfour = Asc(four.Text)
        intfive = Asc(five.Text)
        intsix = Asc(six.Text)

        num1 = (intone + intfive) + 129 + (rndnum / 6)
        ...
    End Sub

    Function setnum()
        Dim intCurrNum As Int16

        Select Case counter
            Case 1
                intCurrNum = num1
        ...
            Case 20
                intCurrNum = num20
                counter = 0
        End Select
        counter += 1
        Return intCurrNum
    End Function

    Function changecurrent(ByVal current As Char) As String

        Select Case current.ToString.ToLower
            Case "a"
                changecurrent = "n"
            ...
...
            Case Else
                changecurrent = current
        End Select
        If current.ToString.ToUpper = current Then
            changecurrent = changecurrent.ToString.ToUpper
        End If
        Return changecurrent
    End Function

   

#End Region