[quickform] Not detect the checkbox value

Hello everybody, I have a Problem with quickform controller, I am using flexy templates for display my form, but I need get from database values of persons for assign a teacher, but for this I need create many checkboxes for assign, the problem is when I press next this checkboxes not adquire the real value, I mean if the user press or not in the check, and for concecuence the values are not real. Do you have an Idea why ocurr this? Thank you so much