plugin produces php errors wp running on iis7

while plugin installs without problem on local environment (xampp) on production Server (iis7) produces php notices (in Administration) and does not install.
Notice: wp_enqueue_script was called incorrectly. Scripts and styles should not be registered or enqueued until the wp_enqueue_scripts, admin_enqueue_scripts, or login_enqueue_scripts hooks. Please see Debugging in WordPress for more information. (This message was added in version 3.3.) in …\httpdocs\wp-includes\functions.php on line 3049
Notice: Undefined offset: 2 in …\httpdocs\wp-content\plugins\my-live-chat-for-wp\plugin_files\MyLiveChatAdmin.class.php on line 270
php version: 5.3.15
it also happens with other Live Chat / support plugins.
any idea how to fix this?
thanks

https://www.ads-software.com/plugins/my-live-chat-for-wp/