Thanks, that fixed the error. But the sub is doing the 1st part of it in
reverse, ie it is updating z from x, when it should be the other way, update
x from z, ref:
update x's col R with the deletion dates in z's col J
for IDs in z which match those in x

The 2nd part is working fine though
For unmatched IDs, .. flag these IDs in z's col K as: "ID not found"