Can not print in an Epson Stylus 640

[Fco Javier Monge Alonso]

I use gs -sDevice=stcolor -sOutputFile=/dev/lp0 -r<720x720> myfile.ps
and I only get white papers
but with gs -sDevice=stcolor -sOutputFile=/dev/lp0 -r<360x360> myfile.ps
no problem.
All this happens went I actialized to slink. Before this all woked OK
What's the problem?. Has it any solution? Thanks