Cat pooing next to box

Rosi my kitten, has been pooing next to the litterbox. We have stuck to the same litter. We also scoop every day. We have another cat Tink. She never did this. We got her newborn.
Please help me, i'm trying to figure out whats wrong. Literaly, this is the 156th website i have checked.

Answer by Kate
Well my first question would be, do you have separate litter trays for your cats?

i ask this because in general cats do not like to share a litter tray because the smell of the other cats urine etc is a territory marker.

The behaviour you describe is not unusual. I would suggest separate litter trays not near each other and also a period of litter training for your cat see this page for details

http://www.our-happy-cat.com/cat-litter-box.html

Also make sure you thoroughly clean the area she has been going on because even the tiniest spot will encourage her to go there again.

http://www.our-happy-cat.com/cat-urine-cleaner.html

best wishes Kate