function checkform () {

//get fields from the form
fname = document.getElementById("first_name").value;
lname = document.getElementById("last_name").value;
title = document.getElementById("title").value;
company = document.getElementById("company").value;
gradelevel = document.getElementById("00N50000001v5P2").value;
email = document.getElementById("email").value;
street = document.getElementById("street").value;
city = document.getElementById("city").value;
zip = document.getElementById("zip").value;
country = document.getElementById("country").value;
phone = document.getElementById("phone").value;
fax = document.getElementById("fax").value;
comments = document.getElementById("00N30000000yLPI").value;

//set error message
errormsg = "Veuillez compléter tous les champs requis."

 if (fname == "" || lname == "" || title == "" || company == "" || gradelevel == "" || email == "" || street == "" || city == "" || zip == "" || country == "" || phone == "" || fax == "" || comments == "")
 {
   //display error message
   alert(errormsg);
   return false;
 }
 else
 {
 
   //set market segment and segment detail
   switch(gradelevel)
   {
   case "Primary":
   
       //set market segment
       document.getElementById("00N50000001v5WD").value = "K-12";
       
       //set segment detail
       document.getElementById("00N300000012FVH").value = "K-8 School";
     
     break;
   case "Secondary":
   
       //set market segment
       document.getElementById("00N50000001v5WD").value = "K-12";
       
       //set segment detail
       document.getElementById("00N300000012FVH").value = "High School";
       
     break;
   case "Higher Education":
   
       //set market segment
       document.getElementById("00N50000001v5WD").value = "Higher Education";
       
       //set segment detail
       document.getElementById("00N300000012FVH").value = "4-year University";
       
     break;
   default:
       //set market segment
       document.getElementById("00N50000001v5WD").value = "";
       
       //set segment detail
       document.getElementById("00N300000012FVH").value = "";
   }
 

  
  //submit the form
  document.regform.method = 'POST';
  document.regform.action = 'https://www.salesforce.com/servlet/servlet.WebToLead?encoding=UTF-8';

 }
}