wrong type error in local variables

[Douglas Lewan <d.lewan2000@gmail.com>]

I have a TeX file with the following local variables:

     Local Variables:
     eval: (ab-new-buffer (prog1 (find-file "chapter16.tex") (message "After find file.")))
     End:

The (find-file) succeeds. (There's a buffer with that file and I see the 
message.) However, overall I get this error:

     File local-variables error: (wrong-type-argument stringp nil)

I assume the call to (ab-new-buffer) gets the error, but as far as I can 
tell that call never happens. (ab-new-buffer) has the following definition:

     (defun ab-new-buffer (buffer-or-name)
       (error "Now in (ab-new-buffer)."))

I never see that error.
What am I missing?

FYI The data above are obviously reduced to a minimal case. With the 
correct definition of (ab-new-buffer) a full battery of tests passes.

-- 
,Doug
d.lewan2000@gmail.com
(908) 720 7908

If this is what winning looks like, I'd hate to see what losing is.