set_value/set_checkbox not keeping the checkbox checked if the form is reloaded.

[eluser]Brad K Morse[/eluser]
the user will initially check the checkboxes, post the form, the user may of forgotten to fill in another field that is required, so it will display the form again, with the fields populated with the data they filled pre-post. The data for all the other fields (text, select, textarea) retain their data, but not the step_id[] checkboxes