questionnaire checkbox disable/enable button + echo

I have problems with my firts questionnaire which works only from checkbox number 1 to 100. I have 2 checkboxes for one question(150 questions are there..) and i need that somewho who will do this questionnaire can´t click on button till he didn´t check one of two checkboxes in each question...Maybe it´s really tidy and bad but i am new in this so sorry :) thanks for help :)Hello, I have problems with my firts questionnaire which works only from checkbox number 1 to 100. I have 2 checkboxes for one question(150 questions are there..) and i need that somewho who will do this questionnaire can´t click on button till he didn´t check one of two checkboxes in each question...Maybe it´s really tidy and bad but i am new in this so sorry :) thanks for help :)[demo][1] http://ift.tt/2skXL0L`