function checkForm(form) {
    
    var el, 
        elName, 
        value, 
        type; 
   
    var errorList = [];
    
    var errorText = {
        1 : "'Name'",
        2 : "'E-mail'",
    3 : "'Message'",
    4 : "'Company name'",
    5 : "'Company phone'",
    6 : "The checkbox must not be blank"        
    }
   
    for (var i = 0; i < form.elements.length; i++) {
        el = form.elements[i];
        elName = el.nodeName.toLowerCase();
        value = el.value;
        if (elName == "input") { // INPUT
          
            type = el.type.toLowerCase();
           
            switch (type) {
                case "text" :
                    if (el.name == "textfield" && value == "") errorList.push(1);
                   
                    if (el.name == "textfield4" && value == "") errorList.push(2);
                    
                break;
                case "file" :
                   // if (value == "") errorList.push(3);
                break;
                case "checkbox" :
                    if(el.name=="C1" && el.checked==false) errorList.push(6);
                break;
                case "radio" :
                   
                break;
                default :
                    
                break;
            }
        } else if (el.name == "textarea") { // TEXTAREA
            if (value == "") errorList.push(3);
             break;
           
        }
    }
   
     if (!errorList.length) {
        _gaq.push(['_trackPageview', '/ContactRequest']);
        return true;
     }
            
   
    var errorMsg = "Please fill those fields:\n\n";
    for (i = 0; i < errorList.length; i++) {
        errorMsg += errorText[errorList[i]] + "\n";
    }
    alert(errorMsg);
    return false;
}