Rails 3 invalid multibyte char (US-ASCII)

I found a similar post here but I can't solve the problem anyway.

I got this

/home/fra/siti/Pensiero/db/seeds.rb:32: invalid multibyte char (US-ASCII)
/home/fra/siti/Pensiero/db/seeds.rb:32: invalid multibyte char (US-ASCII)
/home/fra/siti/Pensiero/db/seeds.rb:32: syntax error, unexpected $end, expecting ')'
... ed il valore della vita, si è malati", :user_id => 1, :cat...

The problem is in this string

:body => "Nel momento in cui ci si chiede il significato ed il valore della vita, si è malati"

I got the problem with every "e" character with the accent, like "è é "

I tried to put magic comment # coding: utf-8 but it doesn't work.

Any idea?