Problem with printing from movieclip

i have set up a flash file in which you press a ‘print’ button and this should print the contents of a movieclip. inside the movieclip i have four frames, each with an image on. the code i have used on the print button is:

on (release) {
    print(a4_print, "bmovie");

the movie clip has the instance name ‘a4_print’. i tested this in another movie and it worked fine! this time it recognises that there are 4 pages to print but just spews out 4 blank sheets of paper… any ideas what could be wrong?