Why my form is not working?

http://sivriist.com/is_ariyorum.html

my form is not working ?

I have checked your form and I can see when you submit it, it only shows a blank page, but when you submit it using the direct link it shows the thank you message. 

I can also see that you have embedded your form using the source code, it seems like you made some changes on the form and did not embed the form again. 

Here is when I submitted your form embedded in your website: 

This is when I submitted your form using the direct link: 

I would suggest you to re-embed your form since I got the fresh source code for your form and I was able to submit it without any issue.

Please follow this advice and if the form still has the issue, let us know, we will be glad to check your form again.