Twitter related issue

Hello,

I am providing a facility where a user can tweet a content along with the url from my site(And it’s working fine.), but Once after tweeting from my site no response I am getting from twitter.

My Question is how do my system will know whether user has posted on twitter or not?

It will be really great if someone can help me.

Thanks
Abhis

You must ask twitter for this. Have you gone through their API?