function checkValues(formName) {
    //get there values
    var frm						= document.forms[formName];
    var bYear					= parseInt(frm['bYear'].value);
    var bMonth				= parseInt(frm['bMonth'].value);
    var bDay					= parseInt(frm['bDay'].value);
    var ageNeeded			= parseInt(frm['ageNeeded'].value);
    var divError			= document.getElementById('error');

    //form validation
    if (frm['bYear'].value.length == 0 || frm['bMonth'].value.length == 0 || frm['bDay'].value.length == 0) { //emptycheck
        divError.innerHTML = 'Vul aub uw geboortedatum in';
        divError.style.display = 'block';
        return false;
    }
    
    //age check
    
    var currentDate = new Date();
    var birthDate = new Date(bYear, bMonth-1, bDay);  //Month is 0-11 in JavaScript
    var oneYear = 1000*365*60*60*24;
    
    var currentAge = (currentDate.getTime()-birthDate.getTime())/(oneYear);
    if (currentAge >= ageNeeded) {
        frm['ageOk'].value = "true";
        return true;
    }
    else {
        divError.innerHTML = 'Je bent helaas te jong om deze site te bekijken. Ga voor meer informatie naar <a href="http://www.genietmaardrinkmetmate.nl">genietmaardrinkmetmate.nl</a>';
        divError.style.display = 'block';
        return false;        
    }
    return true;
}