[solved]How to do terms with checkbox?

[solved]How to do terms with checkbox?

Hi

There is a <input name="checkbox" type="checkbox" value="checkbox" />
and <asp:imagebutton id="buttonRegister" /> in an aspx form.

I added the Ajax script. If I uncheck the checkbox, it would pop up. However, if I checked it, it still pop up.

What's wrong with the code?

$(document).ready(function() {     
$("#ctl00_cphContent_buttonRegister").click(function(e){       
if(!$("#checkbox").is(':checked'))       
{           
alert("you did not check the agree to terms...");           
e.preventDefault();       
}   
});
});