Form-validation, checkbox

Hello,
i have a form and require a couple of fields to be filled out. Everything works fine, but the checkbox. I've tried alot of variations, but i can't get the script to require the checkbox to be checked. In my code bellow, the checkbox is called "accept"
Here is my code, thanks!


$(document).ready(function(){


$("#error").hide();

$("#contactForm #submit").click(function() {
$("#error").hide();



var email = $("input#email").val();
if(email == ""){
$("#error").fadeIn().text("Courriel requis");
$("input#email").focus();
return false;
}

var tel = $("input#tel").val();
if(tel == ""){
$("#error").fadeIn().text("Numéro de téléphone requis.");
$("input#tel").focus();
return false;
}


var accepter = $("input#accept").val();
if(accepter == ""){
$("#error").fadeIn().text("Vous devez donner l'autorisation");
$("input#accept").focus();
return false;
}

var sendMailUrl = $("#sendMailUrl").val();


var to = $("#to").val();
var from = $("#from").val();
var subject = $("#subject").val();

var dataString = 'email='+ email

+ '&email=' + email
+ '&tel=' + tel
+ '&accept=' + accept
+ '&to=' + to
+ '&from=' + from
+ '&subject=' + subject;
// ajax
$.ajax({
type:"POST",
url: sendMailUrl,
data: dataString,
success: success()
});
});


function success(){

$("#disapear").hide();
$("#disapear2").hide();
$("#disapear3").hide();
//$("#contactForm").fadeOut();
$("#success").fadeIn();
$("#success2").show();

}



return false;
});