Search form on Theme Problem

Hi. I have a big problem, first i thought it was the search form bugged, so I got new widgets but the same problem persists and I found out it is the theme problem.

If i change my theme to the one that i desire my search bar don’t work any more . I really like that theme and i want to stick with it , I think i have to modify something to make it work but i don’t know what.

If you have experience or you need more info I will provide .

I hope you can help me out ..