I see now... I was on the details page.
The issue is that your only recordset on this page is named: $SecurityAssistmembers
but on line 181 you have:
<li class="member">User: <?php echo($rsCurrentUser->getColumnVal("first_name")); ?> <?php echo($rsCurrentUser->getColumnVal("surname")); ?><br>
That recordset doesn't exist on the page.
You should probably store the member name in the session on the login page and use it to display the name where you need to.