function isEmail(email) {
	//var rx = /^..+@..+\..{2,5}$/;
	var rx =/^[_a-zA-Z0-9-]+(\.[_a-zA-Z0-9-]+)*@[a-zA-Z0-9-]+(\.[a-zA-Z0-9-]+)*\.([a-zA-Z]{2,4})$/;
	return rx.test(email);
}


function checkform_contact(){
	if(document.registrationform.first_name.value == "") {
		alert("Please insert your first name.");
		document.registrationform.first_name.focus();
		return false ;
	}
	if(document.registrationform.last_name.value == "") {
		alert("Please insert your last name.");
		document.registrationform.last_name.focus();
		return false ;
	}
	if(document.registrationform.profession.value == "") {
		alert("Please insert a profession.");
		document.registrationform.profession.focus();
		return false ;
	}
		if(document.registrationform.organisation.value == "") {
		alert("Please insert an organisation.");
		document.registrationform.organisation.focus();
		return false ;
	}
	if(document.registrationform.adress1.value == "") {
		alert("Please insert an adress.");
		document.registrationform.adress1.focus();
		return false ;
	}
	if(document.registrationform.city.value == "") {
		alert("Please insert a city.");
		document.registrationform.city.focus();
		return false ;
	}
	if(document.registrationform.zip.value == "") {
		alert("Please insert a postal code.");
		document.registrationform.zip.focus();
		return false ;
	}
		if(isEmail(document.registrationform.email.value)==false){
		alert("Please insert a valid email addresse.");
		document.registrationform.email.focus();
		return false;
	}

	return true ;
}