Twitter search in user's timeline


HI, I want to make an app to search for somo words in users’s timeline.
I’ve made an OAuth autentication and it works fine, for each user I keep the token and token_secret in mi database but when I use these tokens in my search I get the next error:
“Invalid or expired token”, code 89.

What am I doing wrong, this is not the users token that I need to keep?

I’m using the twitteroauth library in my codeigniter proyect.