QADBXREF question

My company recently upgraded their software and my boss wants me to "review
all the files for changes".  Don't ask why I can't just ask the real
programmers - long story.  Anyway, I have a library with the current files
and a library with the old files.  I also have a file that contains the
names of all of our files (and a logical over that for just the physical
files).  So I thought I would just read my file with the physical file names
and chain to the QADBXREF to figure out the number of fields and/or the
record length.  The key to QADBXREF is the library name and the file name.
I would just chain to QADBXREF with the old library/file name and then chain
with the new library/file name and if there was a difference in the record
length/number of fields there would be a good chance that the file had been
changed.  So I do my chain to QADBXREF and I don't get a hit.  I know the
key is correct.  And I know the record exists in the QADBXREF file.   Is
there something special about QADBXREF?

Thanks

DT