setting defaults not working

[tj]

I am trying to use glabels to print to a networked printer, using CUPS on a machine named misty,  and I am having a problem with margins on my Brother HL-1440 printer.

I am using PC Papers by Amrad buisness card stock which states to use template #5371 on Windows. So I choose Avery #5371 under glabels and print to 1440 at misty with guide lines and crop marks to plain paper and compare to the stock. The printer printed the top guide line of 11/72 and the card stock perforation is 34/72. I work out the top margin using the 1440's printable area and get 21/72.  I then enter:

#lpoptions -p 1440 at misty -o page-top=21
#lpoptions -p 1440 at misty
page-top=21

But, when I try again, there is no difference. The guide lines were in exactly the same place, i.e. the top margin did not change. So, how do you get the top margin to change?

Also, do the margin option widths start at the page edge, or the "printable area" boundary of the printer on the paper?

tj