set_value() of form validation doesn't work for 2nd time

[eluser]Unknown[/eluser]
Hi,

* I have a form using set_value() to repopulate previous value. (using CI 2.0.2)

* e.g. If a user forgot to fill in a field, he clicks submit button. There is error message for that empty field. There other fields' value will be repopulated.
* If the user fix his error, but he changes his mind and he modifies some of the existing fields, the values of them are actually old values (i.e. set_value only populates the very first value, it never keep the newer value)

* Is it just me or other get the same problem?