Form validation config vs set_rules

[eluser]Aken[/eluser]
I'm thinking maybe the first method isn't working at all. Maybe NO rules are being set in the first case, which would result in no errors.

If you're submitting two different sets of data to the same controller, you should use rule sets to specify which data to compare. So you'd need to have two instances of $this->form_validation->run(), with each run() specifying a rule set. See "Creating Sets of Rules"