Suppress printing of blank records

Question

This should be simple, but I have tried everything I can think of, and trolled through the archives, without finding an answer.  Please don't chastise me for asking a question which has already been answered, too simple, in the wrong section, or any of the other sins you regularly accuse us of...
I am printing a series of form letters which are selected on the basis of a couple of criteria.  I want to exclude records with blank fields.  (My database supports null values, but these field entries are blanks, not nulls.  The fields are string (alphanumeric) values. My selection criteria (for the 1 month letter) are below.  The first two criteria work fine; it is in the third line that I am trying to exclude the blank records.  I have tried: {LetterEnt.Gr_LastName}<>"",  {LetterEnt.Gr_LastName}<>" ", and then I got clever and tried the entry below.  None of these work.
{LetterEnt.Letter1} = "X" and
{LetterEnt.Site} = "Q" and
Length({LetterEnt.Gr_LastName})>0

Answer 1

+Message: AFAIK, if there are no records, there are no detail sections, so
your report must show text from other sections.+
(Is AFAIK some sort of "geek code" (in which case you have gone completely over my head), or are you addressing somebody by that name?  (My name is David).)
If there are no records, there are indeed detail sections - with blank address fields.  See my previous more detailed exposition of the exact nature of the problem.
+It is also not clear what "forces" a printout.  Are you using Crystal
Designer (my assumption since you are posing in the Crystal Report Design
forum) or something else (Crystal Enterprise)?  Crystal Designer doesn't
force printouts - a user must initiate the printout.+
Am I using Crystal Designer?  I don't know.  The program is called Crystal Reports XI in my computer.  Are you suggesting that I am in fact asking my question in the wrong forum? (I would have presumed that something called "Crystal Reports Design" deals with design issues in Crystal Reports, but if I am in error, I do apologise.  Perhaps you could direct me to the more appropriate resource.)
What "forces" a printout? You are correct insofar as the operator has to push the Print button (at least as presently functioning.  At one stage I had the letters printing out behind the scenes using an Active-X control.  This ran for 2 weeks, then fell apart and I eventually gave up trying to make it work; but that is another story.)  How does this happen?  Crystal is adding completely blank pages as the first page on some of the reports, so it is not always immediately apparent to the operator that there is a letter sitting there with a blank address.  (And this, too, is a separate issue.  I have gone through all the instructions in the knowledge base as to how to get rid of the leading blank sheet.  None of the instructions have worked, and I eventually gave up trying.  Thinking about it, I have had an awful lot of frustration with this program.  Perhaps I am unreasonable, but if I can't get something to work after 3 or 4 hours' trying, I give it up as a bad job and live with the fault.)
+You can always suppress those other sections with a condition such as
IsNull({some field that is never Null).+
It is not clear to me what this means.  All the sections other than the detail section are blank - always.
+There are 3rd-party Crystal Reports tools that allow you to skip
processing (printing/exporting/emailing) if the report comes up with zero
records.+
Aha!  Am I interpreting this correctly, as saying that I cannot do what I want to do (suppress printing of letters with blank addresses) in Crystal Reports, and that to do this I need to get a third party add-on?