Filters always disappears

[Laurent HOAREAU]

Hi,
I've got a network printer : KONIKA MINOLTA C220.
This printer uses an internal authentification system.
I try to use a filter (minolta) with the printers.conf :
Filter application/vnd.cups-raw 0 minolta
Filter application/vnd.cups-command 0 commandtops
Filter application/vnd.cups-postscript 0 minolta

But these line always disappeard...

So is there a way to add these lines in the printer.conf file?

Thanks!