email and call_user_function

I have mail code:
function send($head ,$acqu ,$ser ,$hear){ echo "$head ";echo "$acqu ";echo "$ser ";echo "$hear "; }
$to = $email;
$subject = "Here is your Motion";
$message = "$call_user_function_send($head ,$acqu ,$ser ,$hear)";
$headers = "From: PLF<lee@plf.net>rn";

mail($to, $subject, $message, $headers);


It works great if I want my message in script and not the output. what is the problem and suggestions. This is run on a form at http://www.plf.net/motions/form/aquittal.shtml
I know I should be using php instead of ssi but one thing at a time. thank you for any help

Your function should return a string.