Need to print a book with PDF

hello. I'm using Adobe acrobat Pro, and I try to make a printed book off a PDF with

lulu.

now, i already printed some books using their service and they came great the problem is, that some books

have an error that says:

Page Layout: The page size or orientation differs within your PDF. Please ensure that all pages are the same size and oriented the same way (Portrait or Landscape). Learn about print size and orientation 

so i Ctrl-P to print the file using size option "fit" and orientation "portrait" and "all pages" but the problem

persist. i would highly appreciate if someone can tell me how could i print the book with this service is cheap for me.

thanks in advance

[moderator notice: the links look more like spam, removed]