Mike,
the issue lies within the field "bench_cond". In one of your shapefiles it is setup as a string field and in your other shapefile it is setup as a short field. Meaning it can't combine your words into the number field. Rename one of your fields (add a new field with a new name and calculate the new field with the old field and then delete the old field). Or setup both fields to allow numbers and strings, if you need them combined.
The same thing happens with your "through_con" field. It might be all your condition fields actually, since in one shapefile they use numbers as conditions and in the other one words.
Tim