problem with sed substitution

[Olivier Regnier]

Hi everyone,

I try to use sed with /etc/gettytab file. I would like to replace this 
text :
\r\n%s\%m ($h) (%t)\r\n\r by Hello world.
I tested with this command :
% sed -i.old -e 's/\r\n%s\%m ($h) (%t)\r\n\r/Hello world/'
but that doesn't work at all.
Can you help me please ?

Thank you :)