All links on Facebook App are not clickable

Hello, I have Facebook App and web site. Facebook App : [login to view URL] Web site : [login to view URL] In Facebook App, we insert website url to Canvas Url Until a few weeks, Facebook app and web site are working well. i think. My Problem seems to be Iframe issue (target issue) or Facebook bug. 1) Web site is still working well. 2) In Facebook App, when i click all links, these links didn't work well. But, when i open with new window, it would work well. I recognize this problem is target problem in html. So, i forcefully put the "base target = _top" in every page. After that, links problem was solved in almost Browsers (Chrome, FF, Safari, etc...) But other issue happened. I think it's not good solution. So, i removed base target tags. Could you help? I think it's not server issue and program issue because .... when i click one of all links on FB app, no traffic to our server. Our System is made by JAVA, Spring framework. Brian.