Not sure... did you look at the help.php file?
There's this bit:
Code:
$fillerror = (empty($contact["firstname"]) || empty($contact["lastname"]) || empty($contact["b_address"]) || empty($contact["b_city"]) || empty($contact["b_country"]) || empty($contact["b_zipcode"]) || empty($contact["phone"]) || empty($contact["email"]) || empty($contact["subject"]) || empty($contact["body"]));
Maybe you need to take some fields out of there so it doesn't produce an error when it looks for something that isn't there????