code not working to highlight a cell if blank

I have a bit of code that should find a blank cell within a column and paint that cell as a color 6 (color of a yellow highlighter).

   Dim blank As range, LR1 As Long, z As Long
        For Each blank In range("AG2", range("AG" & Rows.Count).End(xlUp))
        If UCase(blank.Value) = "" Then
           range(Cells(blank.Value)).Interior.ColorIndex = 6
          End If
        Next blank
    LR1 = Cells(Rows.Count, "AG").End(xlUp).Row
    For z = LR1 To 2 Step -1

Basically, if any cell within the column "AG" has been left blank, I need just that cell highlighted. I am a beginner and came up with this code by piecing together other code that has worked for me. I think the "UCase" is wrong but I don't know what to put in its place. Is that all?
Thanks.