VB Script search within a column in one Wb and find in another WB and Highlight yellow

Is something wrong with the way I entered it. I only want to search text in A1:A500 then find each cell within that range in A1:A5000 in the other workbook and highlight it Yellow

Sub DixieDiver()
Dim x As String
Dim i As Long
Dim y As Range
For i = 2 To Range("A" & Rows.Count).End(3).Row
    x = Range("A" & i).Value
        Set y = Workbooks("Missing PI Tags 20141021b.xlsx").Sheets("Jacobs").Cells.Find(x, LookIn:=xlValues, lookat:=xlWhole)
            If Not y Is Nothing Then
                Workbooks("DB (Old App).xlsx").Sheets("DB (Old App)").Cells(y.Row, y.Column).Interior.ColorIndex = 6
            End If
        Set y = Nothing
Next i

End Sub