PHP Find String in CSV file

I've got a large flat file of usernames and emails in the following format:

"username", "email"
"username", "email"
"username", "email"

etc...

I need to take the email and search for the username, but for some reason it will not return a result. It works if I search opposite.

$string = "user_email@something.com";
$filename = "user_email.txt";
        $h = fopen("$filename","r");
        $flag=0;

        while (!feof ($h)) {
            $buffer = fgets($h);
            $thisarray = split(",", $buffer);

            if ($string == str_replace('"','', $thisarray[1])) { 
                $i = 1;
                $i++;
                echo '<td bgcolor="#CCFFCC"><b style="color: maroon">' . str_replace('"','',$thisarray[0]). '</b></td>';

                }   

Any ideas? Thanks!