Query builder|advanced: ORDER BY custom field?

I have a custom field that is shared by both queues in our RT database: CONVreq.

Of course it isn’t available in the query builder 'display columns’
section because I haven’t limited the query to include ‘queue’.

No problem; I was able to add it to the list of fields displayed by
putting this in lower box of the Advanced view:

Now, about the ‘order by’ clause… It’s the same problem, but I
don’t have any examples of how to specify ORDER BY in the Advanced
query builder.

Any help?

Phil Lawrence