A little more information. The following names work:
1.pdf
1-HC.pdf
Bk 1-A.pdf
FCBD 2013.pdf
1-HC-2.pdf
These names do NOT work:
Bk 1-HC.pdf
Dlx 1-HC.pdf
Just ending in HC works successfully.
But if there is a <space> in the name AND it ends with HC, it doesn't work.