Too big increment files

[Iván Renedo Chantres]

Hi, i want to use rdiff-backup for keeping and send the increment files over
internet, but i have a problem: i´m making proves with a 17 MB Word document
and changing only a few word, the increment file is 17 MB.
I know that the problem is on rdiff, i have make this proves with this one
only and the result is the same: a 17 MB increment file ( i prove whit
changing the block size, but nothing change).
Is very important for me make a small increment files, and so, i someone
knows where the problem is, i will be very gratefully.
If the quiestion has to be asked on other mailing list, let me know the
address.
Thanks for your help.

		Iván Renedo