epub to pdf conversion using calibre

[rblearn]

I am a newbie to calibre and I am trying to convert from epub to pdf. Seems like the conversion is good apart from 2 issues

1. I cannot seem to add in a space at the top and bottom of the page. So, it seems that --margin-bottom=72 and --margin-top=72 does not add in a space
(Note, I do not have the option of remove spaces between paragraphs checked)

2. Blank spaces are inserted between every new Chapter

Here is how my command line looks
ebook-convert <input book> <output_book.pdf> --custom-size=9x11 --pretty-print --insert-blank-line --margin-bottom=72 --margin-left=72 --margin-right=72 --margin-top=72 --verbose --verbose

Any help to understand why I get blank pages (I did see a bug logged on this??) and most important do not get the 1 inch at the bottom and top of page will be much appreciated

rb