How to let C-s center the line

[Timur Aydin <sdfeklsdf@sadfoweklsdfs.cdweeds>]

Hi,

I am trying to advice the isearch-forward function so that when I
search for a string and that string is found in the buffer, I want
that line to be centered. When I hit C-s again to find the next
instance of the string, that line should also be centered.

Here is what I wrote in the scratch buffer:

(defadvice isearch-forward (after my-isearch-forward-with-center activate)
        (recenter))

Then I have evaluated this, but C-s behaves exactly the same was as before...

Is this the proper way of achieving my goal, or am I way off?

-- 
Timur Aydin