Replace Array with Array

[Arightwizard]

Hi, I'm trying to make a project for a type of encryption - but one of the steps is screwing up.
This is my code: (The step that is screwing up)

    Public Sub l2n(ByVal origtext As String)
        Dim old As Array
        Dim newtxt As Array
        old = {"A", "B", "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M", "N", "O", "P", "Q", "R", "S", "T", "U", "V", "W", "X", "Y", "Z", "a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k", "l", "m", "n", "o", "p", "q", "r", "s", "t", "u", "v", "w", "x", "y", "z", "!", "?", """", ",", ":", ";", ".", "`", """, ""+", "-", "*", "@", "#", "$", "%", "^", "&", "(", ")", "{", "}", "[", "]", "/"}
        newtxt = {"1", "2", "3", "4", "5", "6", "7", "8", "9", "10", "11", "12", "13", "14", "15", "16", "17", "18", "19", "20", "21", "22", "23", "24", "25", "26", "1", "2", "3", "4", "5", "6", "7", "8", "9", "10", "11", "12", "13", "14", "15", "16", "17", "18", "19", "20", "21", "22", "23", "24", "25", "26", "27", "28", "29", "30", "31", "32", "33", "34", "35", "36", "37", "38", "40", "41", "42", "43", "44", "45", "46", "47", "48", "49", "50", "51", "52"}
        Replace(origtext, old, newtxt)
    End Sub

However apparently an array cannot be converted into a string, and with 52 values (as well as 26 being repeated once) I really do not wish to go through and type a replace for each and every string.
Thanks,
-Arightwizard
(Visual basic 2010 - .net 4.0 framework)
**Edit** Never mind, I think I got it.
***Edit*** OK, it isn't working for me. Can someone respond?