Hi,
I have an existing lsmb 1.2 system that started to print PDF to the file name _stdin_.pdf. This used be a file name containing the invoice number. The file created is a valid pdf document. I did make some changes to perl on this ubuntu 12.04 system.
To verify I set up a fresh debian wheezy using lsmb 1.3.34 and to my surprise the same happens there. A PDF is printed to _stdin_.pdf and is a valid PDF document and when I print to screen all is ok as well. In both systems I noticed in the error.log of apache: Use of uninitialized value in lc at /usr/share/perl5/LaTeX/Driver.pm line 137.