problem with speller pages

hi
i am using speller pages for spell checker. But when I click on spell checker link i am getting error that
"Error executing 'C:ProgramFiles ASpell inaspell.exe' -a--lang=en_US --encoding=utf-8 -H
--rem-sgml-check=alt <./asp7A.tmp 2 >&1
Error: No word list can be found for the language'en_US' "

Please help me very urgent

Thanks