use of ajax $find method

Might be a daft question but have you added a script manager to your master page?

If you have, have you used the script explorer to make sure that the JS class has been built with the script descriptors for your control?

Post your master page markup, it might help.

Just thought of something else, $find uses the client id of your control. The content place holder in a master page will add prefix to your custom control id. Get the ClientID of your grid and try $find with that instead.

Thanks guys.

I found the problem. i am using Jquery in my page, and relied on their pageLoad like function, as it appears this function is activated before the ajax library is fully loaded.