Media button Thickbox content doesn’t work everywhere

I ended up solving this by changing my two functions to only one, and setting the “button” to show the iframe directly, like this:

function add_custom_media_button() {
    $cu = wp_get_current_user();
    $cusername = $cu->user_login;
    $clocale = get_locale();
    echo '<a href="http://nephila.cloudapp.net/GAdEWeb/wpsearch.aspx?wpuser=" . $cusername . "&wplang=' . $clocale . '&TB_iframe=true&width=800&height=600" id="insert-my-media" class="button thickbox">Add custom media</a>';
}
add_action('media_buttons', 'add_custom_media_button', 15);