Unsupported file format for

[Myska Ludek]

Hi.I wrote my own filter to save print file before processing and i use tea4cups as backend for copy jobs to another printer.Work well but cups say in log:
"Unsupported file format for /var/spool/cups/tmp/tmpLQg55R (input file /var/spool/cups/tmp/tmpLQg55R is empty !)"
The name of tmpfile is different per job.If i use only tea4cups or only my filter the error message still the same.where is the  problem ?.
Cups 1.4.4 Samba 3.5.6 Debian Gnu/Linux 6 i386.Samba is connected to ads domain with winbind.