4 week old kittens won't poop!!!!

I am fostering 4 week old kittens...and the only way i can get them to poop is to stimulate them..they will not go on there own. I waited almost 3 days to see if they would and I had to help them out. It is very firm...should I be givin them more water? They are not to happy about trying to eat froma dish, they love there bottle. I try to put gruel in the bottle to thicken up the formula and give them something besides just plain formula. Here are some pics of my foster babies!

http://http://i144.photobucket.com/a...Picture209.jpg
http://http://i144.photobucket.com/a...Picture213.jpg
http://http://i144.photobucket.com/a...Picture210.jpg
http://http://i144.photobucket.com/a...Picture212.jpg

iv had kittens still needing to be stimulated at 6 weeks old!! i think it depends on the kitten , my four week old ones still need there mum to do it for them , no signs of them wanting to go on there own , normally once they start eating on there own is when they start going toliet on their own.
if its very firm , there is something you can put into their milk , but i can never remember what it is called, i will go over some of the other posts and see if i can get the name of it. but dont worry to much at this point if they still need help. good luck.

ps , i can not view you pictures? says error?

I am putting new pictures on this post of the Kittens








Holding my own bottle!!!

aww there beautiful.