Problems assigning value to an array: Run-Time error 9

[nai0248]

Code is below:

Trying to read the value of a cell to put only unique values into an array for later uses.

Sub Unique()
Dim ARComputer() As String, ARAssign() As Variant, I, intRow, intLastRow, x
I = 0: r = 0

intLastRow = Range("A65536").End(xlUp).Row

ARComputer(I) = Cells(intLastRow, 1).Value ' Error occurs at this line Trying to assign first value and then use this later to compare to other values

For intRow = intLastRow To 2 Step -1
    Rows(intRow).Select
    If ARComputer(I) <> Cells(intRow, 1).Value Then
        I = I + 1
        ReDim Preserve ARComputer(I)
        ARComputer(I) = Cells(intRow, 1).Value
    End If
Next intRow

End Sub