function checkData() {

	var problem = 'no';
	
	var alert_text = "Please fill in the following blank field(s):\n";
	
	if (document.referral.first_name.value.length <= 0) {
		document.getElementById("first_name").className += " error";
		document.getElementById("err").style.display = "block";
		problem = 'yes';
		alert_text += "First name\n";
	}
	
	if (document.referral.last_name.value.length <= 0) {
		document.getElementById("last_name").className += " error";
		document.getElementById("err").style.display = "block";
		problem = 'yes';
		alert_text += "Last name\n";
	}
	
	if (document.referral.street.value.length <= 0) {
		document.getElementById("address").className += " error";
		document.getElementById("err").style.display = "block";
		problem = 'yes';
		alert_text += "Address\n";
	}
	
	if (document.referral.city.value.length <= 0) {
		document.getElementById("city").className += " error";
		document.getElementById("err").style.display = "block";
		problem = 'yes';
		alert_text += "City\n";
	}
	
	if (document.referral.zip.value.length <= 0) {
		document.getElementById("zip").className += " error";
		document.getElementById("err").style.display = "block";
		problem = 'yes';
		alert_text += "Zip\n";
	}
	
	if (document.referral.phone.value.length <= 0) {
		document.getElementById("phone").className += " error";
		document.getElementById("err").style.display = "block";
		problem = 'yes';
		alert_text += "Phone\n";
	}
	
	if (problem == 'no') {
		return true;
	} else {
		alert (alert_text);
		return false;
	}
	
};