did you set the movie export properties on the movie clip? If you do not know what that is then right click the movie in the library and choose "inkage..." Then type a name into the box. Then, your attach statement should look like this.
Code:
_root.attachMovie("submenu linkage name", "submenu new name" level);
so you're missing quotes and thats it if your export linkage name is submenu.
Good luck