Need help in highlighting NULL Values

Hi...

I need a condition in my webpage that if the LOGIN fields is NULL.
That row will be highlighted in RED.

i try this code but it did not work...


$LOGIN = $DTR->fields['LOGIN'];

if($LOGIN == NULL){

 "<td style='background-color:RED'>";

//echo '<style = background-color: RED;>'.$DTR.'</style>';

}

I have this code:


<?php


include 'config.php';


$currentEmpID = $_SESSION['empID']; 

 

 if(!isset($_POST['Regsubmit_'])){ 

     

    $DATE1 = $_GET['Regfirstinput'];

    $DATE2   = $_GET['Regsecondinput'];



 $sql = "SELECT a.EMP_NO, CONCAT(LNAME, ', ' , FNAME, ' ', MI) AS FULLNAME, a.LOGIN, a.LOGOUT

 FROM $ATTENDANCE.employee_attendance AS a LEFT JOIN $ADODB_DB.employment em ON a.EMP_NO = em.EMP_NO 

 LEFT JOIN $ADODB_DB.personal p ON em.EMP_ID = p.EMP_ID WHERE DATE(LOGIN) BETWEEN '$DATE1' AND '$DATE2' 

 AND em.STATUS IN ('Reg Operatives', 'Reg Staff ') OR LOGIN IS NULL";  


    $DTR = $conn3->GetAll($sql);

    

$LOGIN = $DTR->fields['LOGIN'];


if($LOGIN == NULL){

 "<td style='background-color:RED'>";

//echo '<style = background-color: RED;>'.$DTR.'</style>';

}   

$smarty->assign('attendance', $DTR);


 }

 $smarty->display('header_att.tpl');

 $smarty->display('RegAttendance.tpl');

 $smarty->display('footer.tpl');

  

?>


<div id="attendance" style="width: 580px; height: 420px; overflow: auto; padding: 5px; top:95px">

<fieldset>

<legend>Employee Attendance</legend>

<table border="1">

<tr>

<td colspan="2" style="text-align:center">Employee No</td>

<td colspan="2" style="text-align:center">Employee Name</td>

<td colspan="2" style="text-align:center">Time In</td>

<td colspan="2" style="text-align:center">Time Out</td>

</tr>


{section name=att loop=$attendance}

  <tr>

    <td colspan="2">{$attendance[att].EMP_NO}</td>

    <td colspan="2">{$attendance[att].FULLNAME}</td>  

    <td colspan="2">{$attendance[att].LOGIN|date_format:"%d-%m-%Y %I:%M %p"}</td>

    <td colspan="2">{$attendance[att].LOGOUT|date_format:"%d-%m-%Y %I:%M %p"}</td> 

  </tr>

{sectionelse}

  <tr><td colspan="1">No DATA</td></tr>

{/section}

</table>

</fieldset>

</div>

Thank you