[Plugin: All in One SEO Pack] "Advertisement" on title

hi, i don’t understand why my blog title on gogle serps is
“Advertisement – Corso per tecnico del suono” instead of
“Corso per tecnico del suono”

In my blog does not appear “Advertisement”, serching in google “corso tecnico del suono” it appears!

I have several blog using all in one seo pack, i have never had this problem but in this blog http://www.scuolasuono.it/corsotecnicodelsuono/

Please, can you help me?

http://wordpress.org/extend/plugins/all-in-one-seo-pack/