Substitution Cipher Solver

[josh wood]

I am trying to make a substitution cipher solver in vb.net but whenever I try to solve a cipher text using methods other than shift it goes back to the original. This is the code I have so far

Dim Ctl As Control, nAsc As Int16
        For Each Ctl In Panel2.Controls
            If TypeOf (Ctl) Is TextBox Then
                nAsc = Asc(Microsoft.VisualBasic.Left(Ctl.Name, 1))
                If Reverse.Checked = False Then
                    nAsc = nAsc + Shift.Value
                Else
                    nAsc = 90 - nAsc + 65 + Shift.Value
                End If
                If nAsc > 90 Then nAsc = nAsc - 26
                If nAsc < 65 Then nAsc = nAsc + 26
                Ctl.Text = Chr(nAsc)
            End If
        Next
        SolutionSubstitution.Text = EncryptionSubstitution.Text
        Dim sourceChar As Char
        For Each Ctl In Panel2.Controls
            If TypeOf (Ctl) Is TextBox Then
                sourceChar = Microsoft.VisualBasic.Left(Ctl.Name, 1)
                SolutionSubstitution.Text = SolutionSubstitution.Text.Replace(sourceChar, Chr(Asc(Ctl.Text) + 128))

            End If
        Next
        For Each Ctl In Panel2.Controls
            If TypeOf (Ctl) Is TextBox Then
                sourceChar = Chr(Asc(Microsoft.VisualBasic.Left(Ctl.Name, 1)) + 128)
                SolutionSubstitution.Text = SolutionSubstitution.Text.Replace(sourceChar, Microsoft.VisualBasic.Left(Ctl.Name, 1))

            End If
        Next

does anyone have any suggestions

as you can see from the attachments when I press solve it goes back to the original text