CUPS not printing last piece of job

[Dries]

I installed CUPS 1.5.4 (last version available on the platform) with openWRT on a TP link WR2543ND. Everything went fine, except the printer skips the last piece of a job it has to do. First it turns vague, then nothing anymore is printed.

http://driesbeyens.be/dump/scan.pdf
This is the last page of a 10-pages Word document. The top part gets printed last. You clearly can see the intensity of black decreases, and than nothing is printed anymore.

The printer is a Canon IP4850, I've installed canon-bjnp package. This phenomenon occurs both printing from windows and mac clients. Any help?