default avatar image

I want to use my own default avatar, I’ve tried all of the solutions, but my internet is too slow to load gravatar, so no matter what I do I get the broken image link. Here is my code:

/* Powerusers Gravatar
/* ----------------------------------------------*/
add_filter( 'avatar_defaults', 'newgravatar' );  

function newgravatar ($avatar_defaults) {
     $myavatar = get_bloginfo('template_directory') . '/images/no-image.gif';
     $avatar_defaults[$myavatar] = "Powerusers Gravatar";
     return $avatar_defaults;
}