Problem with id's


please can some one advise to how to solve this problem :

i am useing acts_as_ferret to index 3 active record models
the problem is it’s mixing up the id’s from the models
ie one model contains ids up to 45 and the other only up to 10 if
i search on the smaller one it’s gives the error item with id 45 not
found is there any way to fix this ?