Change default post excerpt length?

Hi there,

I’d like to change the default excerpt length, currently set at 55 words. I tried adding this code to the functions.php file, but it didn’t work:

function custom_excerpt_length( $length ) {
return 65;
}
add_filter( ‘excerpt_length’, ‘custom_excerpt_length’, 999 );

Is there a different solution?

Thanks!
Devon