Another problem with MySQL - simple registration form gives blank screen, no errors

Okay, believe me I have been sitting here for a long time staring at this. I can't for the life of me figure out what is wrong.

I get no error message even with them turned on. When I take away the die statements it displays the text at the end so it's definitely an SQL error. Gah I hate SQL!

<?php

include('functions.php');

if(!$_POST['regtype'] || !$_POST['regemail'] || !$_POST['regpass'] || !$_POST['regpass2']) {
"You didn't fill out a required field.";
exit();
}
if($_POST['regpass'] != $_POST['regpass2']) {
"Your passwords didn't match.";
exit();
}


$regtype = protect($_POST['regtype']);
$regemail = protect($_POST['regemail']);
$regpass = protect($_POST['regpass']);
$secregpass = sha1($regpass);
$regdate = date("Y/m/d");


// seems to be right below here

$checksql = "SELECT * FROM profile WHERE email = '$regemail'";
$checkquery = mysql_query($checksql,$connect) or die(mysql_error());
$checknumrows = mysql_num_rows($checkquery) or die(mysql_error());
if($checknumrows > 0) {
    "A user with that email already exists!";
    exit();
} else {

    $inssql = "INSERT INTO profile (email, pass, type, regdate) VALUES ('$regemail', '$secregpass', '$regtype','$regdate')";
    $insquery = mysql_query($inssql, $connect) or die(mysql_error());


    //these are just some of my notes       
    //need to make confirmation mail script later - or use donation verification as everything. def need to set up mail server


    $_SESSION['email'] = $regemail;

    echo "You have successfully registered.
            <br /><br />
            You're almost done! Please pick the charity you would like to donate to, and how much you would like to donate (minimum of $25).
            <br /><br />
            If you can't decide, you can donate to our general fund, which is equitably distributed to each charity (and is not handled by us!).
            <br /><br />
            <form action='donate.php' method='get'>
            Charity:
            <br />开发者_JS百科;<br />
            <select>
            <option name='charity' value='1'>Charity 1</option>
            <option name='charity' value='2'>Charity 2</option>
            <option name='charity' value='3'>Charity 3</option>
            </select>
            <br /><br />
            USD: $<input type='text' name='amount' />
            ";
}


?>

By the way, here's the 'protect' function:

function protect($string){
$string = trim(strip_tags(addslashes($string)));
return $string;

}

brad, this was probably the problem;

$checknumrows = mysql_num_rows($checkquery) or die(mysql_error());

if profile doesn't contain the given email, mysql_num_rows($checkquery) will be 0 so it executes die(mysql_error()) but there's no error so the die() doesn't print anything. In short, get rid of or die(mysql_error())