function checkform() {
                             var error_message="";
                             if (document.gb_form.gb_company && document.gb_form.gb_company.value=="") {
                                                          error_message +="Firma\r\n";
                             }
                             if (document.gb_form.gb_title && document.gb_form.gb_title.value=="") {
                                                          error_message +="Titel\r\n";
                             }
                             if (document.gb_form.gb_firstname && document.gb_form.gb_firstname.value=="") {
                                                          error_message +="Fornavn\r\n";
                             }
                             if (document.gb_form.gb_lastname && document.gb_form.gb_lastname.value=="") {
                                                          error_message +="Efternavn\r\n";
                             }
                             if (document.gb_form.gb_address && document.gb_form.gb_address.value=="") {
                                                          error_message +="Adresse\r\n";
                             }
                             if (document.gb_form.gb_postcode && document.gb_form.gb_postcode.value=="") {
                                                          error_message +="Postnummer\r\n";
                             }
                             if (document.gb_form.gb_city && document.gb_form.gb_city.value=="") {
                                                          error_message +="By\r\n";
                             }
                             if (document.gb_form.gb_email && document.gb_form.gb_email.value=="") {
                                                          error_message +="Email\r\n";
                             }
                             if (document.gb_form.gb_email.value.indexOf("@") == -1 || document.gb_form.gb_email.value.indexOf(".") == -1 || document.gb_form.gb_email.value.indexOf(" ") != -1) {
                                                          error_message += "Korrekt email adresse\r\n";
                             }
                             if(error_message !=''){
                                                          error_message='You need to fill in:\r\n' + error_message + '\r\n';
                                                          alert(error_message);
                                                          return false;
                             }
  }