Need a profilefield in a SQL query in memberlist.php

[ganima]

Hi, there is a little query that drives me nuts I can't get it working.

In /memberlist.php I want the letter links (# A-Z) to look in a custom field not in username.
At line 337 I changed the code to ?

PHP Code:

if ($ltr != '')
    {
        if ($ltr == '#')
        {
            if ($sortfield == 'nachname')
            {
                $condition .= "field7 NOT REGEXP(\"^[a-zA-Z]\")";
            }
            else
            {
                $condition .= "username NOT REGEXP(\"^[a-zA-Z]\")";
            }
        }
        else
        {
            $ltr = chr(intval(ord($ltr)));

            if ($sortfield == 'nachname') 
            {
                $proffid = $profilefield[profilefieldid][7];
                $condition .= $proffid.' LIKE("' . $db->escape_string_like($ltr) . '%")';
            }
            else
            {    
                $condition .= 'username LIKE("' . $db->escape_string_like($ltr) . '%")';
            }
        }
    } 


? but the profilefieldid is always empty. I even can not change it to

PHP Code:

$condition .= 'field7 LIKE("' . $db->escape_string_like($ltr) . '%")'; 


That makes a SQL error and says there is no field named field7.

What's wrong with that? How do I have to change my code to get the profilefield #7 to look at?

Hope for help. And thanks!