As vbe says, cron knows nothing about your environment (and it is NOT doing an interactive login) on your account. It's not going to run your .profile or .bashrc at all.
So you need to set any variables you need (eg. the one's you've put in your .profile and .bashrc) at the start of the script that cron runs.
Also, set any path(s) that are needed to find stuff in the script too.