MySQL Add not picking up one field - php

Question

I am doing a project to add, update, delete, etc records from a p2pmyadmin database.
I am working on the current code. When update is hit, all the fields update in the database, except the 'Surname' field. I cannot figure out why... Can anyone advise?
$dirtyPassword = $_POST['frmPassword1'];
if (isset($_POST['formName']) && $_POST['formName'] == "addUser") {
if ( ($_POST['frmSurname'] != '') &&
($_POST['frmEmail'] != '') &&
($_POST['frmPassword1'] != '') ) {
if ($_POST['frmPassword1'] != $_POST['frmPassword2'] ) {
echo "Passwords do not match!";
//Clean form values
$cleanFirstName = mysqli_real_escape_string($db, $_POST['frmName']);
$cleanSurname = mysqli_real_escape_string($db, $_POST['frmSurname']);
$cleanEmail = mysqli_real_escape_string($db, $_POST['frmEmail']);
//Clean password
$password = sha1(mysqli_real_escape_string($db, $_POST['frmPassword1']));
// Build username
$username = strtolower($cleanFirstName.substr($cleanSurname,0,1));
$dateTime = date('Y-m-d g:i:s',time());
// Check email is unique
$QryEmail = "SELECT *
FROM registeredUsers
WHERE EmailAddress = '$cleanEmail'";
$chkEmail = mysqli_query($db,$QryEmail);
$numChkRowsE = mysqli_num_rows($chkEmail);
// Check Username is unique
$QryID = "SELECT *
FROM registeredUsers
WHERE UserName = '$username'";
$ChkID = mysqli_query($db,$QryID);
$numChkRowsI = mysqli_num_rows($chkID);
//check that zero records returned (no duplicates)
if ($numChkRowsE == 0 && $numChkRowsI == 0){
//Query
$query = "INSERT INTO registeredUsers VALUES(NULL, '$username', '$cleanFirstName', '$cleanSurname', '$cleanEmail', '$password', '$dateTime', 0) ";
$insQry = mysqli_query($db,$query);
if ($insQry) {
/* SUCCESS */
$_SESSION['success'] = 'Registration successful';
header("Location:project-users-manage.php");
exit;
} else {
/* FAIL */
}
}
}
?>
<fieldset style =width:30%>
<form method="post" action="">
<p>
First Name : <input type="text" name="frmName" value="" placeholder='First Name'><br>
Surname: <input type="text" name="frmSurname" value="" placeholder='Surname'><br>
Email Address: <input type="text" name="frmEmail" value="" placeholder='Email Address'><br>
Password: <input type="password" name="frmPassword1" value="" placeholder='Password'><br>
Repeat Password: <input type="password" name="frmPassword2" value="" placeholder='Password Again'><br>
<input type="submit" name="Register" value="Register">
<input type='hidden' name='formName' value='addUser' />
</p>
</form>
<br>
<a href='project-users-manage.php'>User Management</a>
<a href=''>Logout</a>