VBA error excel "type mismarth"

I used this code to create 100000 string 12 digit unique random numeric numbers

this code

Sub uniqueramdom()

Const strCharacters As String = "0123456789"

Dim cllAlphaNums As Collection
Dim arrUnqAlphaNums(1 To 70000) As String
Dim varElement As Variant
Dim strAlphaNum As String
Dim AlphaNumIndex As Long
Dim lUbound As Long
Dim lNumChars As Long
Dim i As Long

Set cllAlphaNums = New Collection
lUbound = UBound(arrUnqAlphaNums)
lNumChars = Len(strCharacters)

On Error Resume Next
Do
    strAlphaNum = vbNullString
    For i = 1 To 12
        strAlphaNum = strAlphaNum & Mid(strCharacters, Int(Rnd() * lNumChars) + 1, 1)
    Next i
    cllAlphaNums.Add strAlphaNum, strAlphaNum
Loop While cllAlphaNums.Count < lUbound
On Error GoTo 0

For Each varElement In cllAlphaNums
    AlphaNumIndex = AlphaNumIndex + 1
    arrUnqAlphaNums(AlphaNumIndex) = varElement
Next varElement

Range("A1").Resize(lUbound).Value = Application.Transpose(arrUnqAlphaNums)

Set cllAlphaNums = Nothing
Erase arrUnqAlphaNums

End Sub

it work when: Dim arrUnqAlphaNums(1 To 50000) As String

so if : Dim arrUnqAlphaNums(1 To 100000) As String . it not work and eroor "type mismarth"

I have the following code in here http://ift.tt/1HZjEVJ