Packing slip issue - Can't print my.shiprush tempate on 9 x 11 laser

I am unable to print the 'my.shiprush' packing slip on our laser printer without it printing in a 4 1/2" x 4" or so format. I want this to print out 9 x 11 through the software and not the my.shiprush website.

This packing slip is better than the 'classic' packing list which does not: print our logo or print the marketplace.

Is there something I am missing? Thanks!