function control(){
    if ((document.kontakt.lastname.value.length<2)||(document.kontakt.lastname.value=="Last name")){
        alert("Please enter your last name.");
        document.kontakt.lastname.value="Last name";
        document.kontakt.lastname.select();
        document.kontakt.lastname.focus();
        return false;               
    }else if((document.kontakt.email.value.length<2)||(document.kontakt.email.value=="Email")){
        alert("Please enter your email.");
        document.kontakt.email.value="Email";
        document.kontakt.email.select();
        document.kontakt.email.focus();
        return false;
    }else if((document.kontakt.subject.value.length<2)||(document.kontakt.subject.value=="Subject")){
        alert("Please enter a subject.");
        document.kontakt.subject.value="Subject";
        document.kontakt.subject.select();
        document.kontakt.subject.focus();
        return false;
    }else if((document.kontakt.text.value.length<2)||(document.kontakt.text.value=="Text")){
        alert("Please enter a text.");
        document.kontakt.text.value="Text";
        document.kontakt.text.select();
        document.kontakt.text.focus();
        return false;
    }
}