Error with code to delete rows based on cell contents

[NKlawender]

I ran this code lasst month and it worked perfectly, now this month, it is giving me an error. I have no idea why. Any ideas?
Dim LastA As Long
With Sheets("Sheet1")
LastA = .Range("A" & Rows.Count).End(xlUp).Row
Application.ScreenUpdating = False
For r = LastA To 2 Step -1
If .Cells(r, "S") = "<Not defined>" And Cells(r, "T") = "<Not defined>" Then .Cells(r, "A").EntireRow.Delete
If .Cells(r, "S") = "." And Cells(r, "T") = "." Then .Cells(r, "A").EntireRow.Delete
If .Cells(r, "S") = "na" And Cells(r, "T") = "na" Then .Cells(r, "A").EntireRow.Delete
If .Cells(r, "S") = "n/a" And Cells(r, "T") = "n/a" Then .Cells(r, "A").EntireRow.Delete
Next r
End With
Application.ScreenUpdating = True

The red part is what is highlighted when I hit Debug.
Thanks,
Norm

 

[gallen]

There's a missing period after the AND

If .Cells(r, "S") = "<Not defined>" And .Cells(r, "T") = "<Not defined>" Then .Cells(r, "A").EntireRow.Delete

 

[gallen]

Duplicate. Sorry

 

[NKlawender]

Thank you!

 

[NKlawender]

I added the missing periods, but I still get the same error. I ran the exact same code on a smaller (number of rows) spreadsheet and it worked fine. On the larger one, approximately 35000 rows, it gets about a third of the way and then gives me the mismatch (type 13) error. I have no idea why.
Thanks,
Norm