Facebook Page & Forced Surveys

i am looking for a custom facebook fan page's code that can really force people to do cpalead surveys to reach the next step in the page. in absolutely no-case people can reach the last step if they have not really completed the cpalead survey. this is what i need. i know that cpalead has a POSTBACK option...and maybe it can be used to track down if an user really completed the survey or not...anyway the method is not important. what i need more is that you find a way to track the surveys and so force users to really complete 1 cplalead survey if the want to reach the last step... i suppose some creativity from you should be needed to find a solution to this problem..... let me know if you have any idea and can work on this.