Update own Plugin Repository on Multisite

i have a curios problem what i cannot fix.

On the plugin mainfile i defined:

add_filter('pre_set_site_transient_update_plugins', array('moreads_update','check_4_updates'));
add_filter('plugins_api', array('moreads_update','plugin_api_info'),10,3);

The Class Functions:

static public function check_4_updates($checkdata) {
    global $wp_version;

    //var_dump($checkdata);return $checkdata;

    $options = get_option(MABASENAME);
    $options = is_serialized($options) ? unserialize($options) : $options;
    if (empty($checkdata-checked)) {return $checkdata;}
    $args = array(
        'slug' = MASLUG,
        'version' = @$checkdata-checked[MASLUG]
    );
    $request_post = array(
        'body' = array(
            'action' = 'plugin_update_check',
            'token' = !empty($options['token']) ? trim($options['token']) : '',
            'domain' = !empty($options['domain']) ? trim($options['domain']) : '',
            'request' = serialize($args)
        ),
        'user-agent' = 'WordPress/'.$wp_version.'; '.get_bloginfo('url')
    );
    $raw_response = wp_remote_post('http://api.domain.tld/',$request_post);
    $response = false;
    if (!is_wp_error($raw_response)  ($raw_response['response']['code'] == 200)) {
        $response = is_serialized($raw_response['body']) ? unserialize($raw_response['body']) : $raw_response['body'];
    }
    if (!empty($response)) {
        if(strpos(@$response-package, self::$_apiurl) !== false) { // Only API Domain for Update Server allowed
            @$checkdata-response[MASLUG] = $response;
        }
    }
    return $checkdata;
}
static public function plugin_api_info($def, $action, $args) {
    global $wp_version;

    if (!isset($args-slug) || ($args-slug != MASLUG)) {
        return false;
    }

    $options = get_option(MABASENAME);
    $options = is_serialized($options) ? unserialize($options) : $options;
    $plugin_info = get_site_transient('update_plugins');
    $current_version = @$plugin_info-checked[MASLUG];
    $args-version = $current_version;

    $request_post = array(
        'body' = array(
            'action' = $action,
            'token' = !empty($options['token']) ? trim($options['token']) : '',
            'domain' = !empty($options['domain']) ? trim($options['domain']) : '',
            'request' = serialize($args)
        ),
        'user-agent' = 'WordPress/'.$wp_version.'; '.get_bloginfo('url')
    );
    $response = wp_remote_post('http://api.domain.tld/',$request_post);
    if (is_wp_error($response)) {
        $res = new WP_Error('plugins_api_failed', __('An unknown error occured while connecting the plugin-API.').'/ppa href="?" onclick="document.location.reload();return false;"'.__('Try again?').'/a', $response-get_error_message());
    } else {
        $res = unserialize($response['body']);
        if ($res === false) {
            $res = new WP_Error('plugins_api_failed', __('Unknown error.'), $response['body']);
        }
    }
    return $res;
}

The API returned follow objects:

Update:
$erg-slug,
$erg-package,
$erg-new_version,

Plugin-Info:
$erg-slug=array(
    'homepage',
    'name',
    'version',
    'author',
    'last_updated',
    'external',
    'requires',
    'tested',
    'downloaded',
    'package',
    'download_link',
    'sections' = array(
        'description',
        'change_log',
        'other_notes'
    )
);

On the single blog all works fine. If i set a new version, the update will shown on Wordpress Update Page.

But on a multisite Blog i see nothings. I have tried only in one blog on multisite, networkwide and also activate into the first blog, no update available.

If i will check it with

set_site_transient('update_plugins', null);
add_filter('plugins_api_result',function($res,$action,$args){print_r(array($res,$action,$args));return $res;});

my update routine "check_4_updates()" will not call on multisite!

What are happend here, what's wrong?

Thanks, Stefan