Else Or Else If?

Hi,

Is there something wrong with this script below?
I just want the script to recognize the four
required fields. LastName, FirstName etc.
If a field is not completed goto Error page
else goto thankyou page.
________________________________________
on (release) {
if (LastName, Firstname, Company, Email eq "") {
gotoAndStop ("Error");
} else {
}
loadVariablesNum ("http://www.versari.com/sendmail.asp", 0, "GET");
gotoAndStop ("thankyou");
}