Before Record Added - error on return false

Show us your exact code in this event.

I have figured this out.

I am using a session variable created by a custom button before redirecting to the add page:

$values["itemsID"] = $_SESSION["quote2title"];

..and then immediately unset the session variable:
unset($_SESSION["quote2title"]);

...which created the return false error.

The solution is to only unset the session variable if return is true:

$values["itemsID"] = $_SESSION["quote2title"];
//unset($_SESSION["quote2title"]);
if ($values["quote"] == "")
{
$message = "Please add a quote";
return false;
}
else
{
unset($_SESSION["quote2title"]);
return true;
}

The code above is a simplified version of my Before Record Added code but it illustrates the problem and solution for my server side validation when I need to use session variables in $values.