Just a guess... either timing of sending packet or structure of packet.

suggestion... strip code down to one packet command e.g. eject, and necessary modules to implement it, nothing else. Get that to work then add other commands one at a time, checking that they work before adding more.

See this document http://www.8052.com/users/jonled/noob.pdf for posting formatted code. It will help others to help you.

Jon