[js] IE toont div niet na submit

var formOk = false;
    var eersteTest = true;
    function checkFormulier()
    {
        f = document.forms["devraag"];
        k = document.getElementById("knopje");
        ok = true;
        if(!f.elements["vraag"].value) ok = false;
        if(!f.elements["naam"].value) ok = false;
        filter  = /^([a-zA-Z0-9_\.\-\+\~])+\@(([a-zA-Z0-9\-\~])+\.)+([a-zA-Z0-9]{2,4})+$/; // filter for email check
        if(!filter.test(f.elements["email"].value)) {
            ok = false;
            f.elements["email"].style.color = "#cc0000";
        } else {
            f.elements["email"].style.color = "#000000";
        }
        if(ok) {
            k.className = "actief";
            formOk = true;
            if(eersteTest)
            {
                document.getElementById("verstuurForm").style.display = "none";
                document.getElementById("bedankt").style.display = "block";
            }
        } else {
            k.className = "blurme";
            formOk = false;
        }
    }
    function stuurFormulier()
    {
        if(formOk)
        {
            document.forms["devraag"].submit();
        }
    }
    checkFormulier();
    eersteTest = false;