stress.

i cant remember where but i heard that if your snake is stressed they wont deficate(sp?)
is this true? if so does that mean when they use the tolit there nt to stressed out.

I personally don't think this is true at all.
Non-eating is a definite sign of stress, but defecating is something that should always happen and can't really be refused unless theres something up. There should always be urates passing unless there is major dehydration.

Roaming, constant activity, not eating, bad sheds, and hissing can all be signs of stress. Defecation however, can be between every 1-3 weeks, depending on when they feel like it. :]

severe stress could also help contribute to an RI also