function sprawdz_formularz() {
	
		f = document.forms['zamowienie'];
	
		if (!f.elements['data'].value.length) {
			alert("Please enter the date!");
			return false;
		}
		
		if (!f.elements['zleceniodawca'].value.length) {
			alert("Please enter the orderer!");
			return false;
		}
		
		if (!f.elements['adres'].value.length) {
			alert("Please enter the address!");
			return false;
		}

		
		if (f.elements['z_jezyka'].value == f.elements['na_jezyk'].value) {
			alert("You cannot choose the same language!");
			return false;
		}

		return true;
	}