PHP - Function With Time Not Returning

SELECT u.firstname AS 'Name' , u.lastname AS 'Surname', c.shortname AS 'Course', (
            CASE
            WHEN gi.itemname LIKE '%summative%' THEN 'SUMMATIVE'
            WHEN gi.itemname LIKE '%formative 2%' THEN 'FORMATIVE 2'
            ELSE 'MC'
            END) AS 'Assessment', from_unixtime(gi.timemodified, '%d/%m/%y') AS 'Date',
            IF (ROUND(gg.finalgrade / gg.rawgrademax * 100 ,2) > 70,'Yes' , 'No') AS Pass, ROUND(gg.finalgrade / gg.rawgrademax * 100 ,2) AS 'Mark', ROUND(gg.finalgrade / gg.rawgrademax * 100 ,2) AS 'Mark'
            FROM mdl_course AS c
            JOIN mdl_context AS ctx ON c.id = ctx.instanceid
            JOIN mdl_role_assignments AS ra ON ra.contextid = ctx.id
            JOIN mdl_user AS u ON u.id = ra.userid
            JOIN mdl_grade_grades AS gg ON gg.userid = u.id
            JOIN mdl_grade_items AS gi ON gi.id = gg.itemid
            JOIN mdl_course_categories AS cc ON cc.id = c.category
            WHERE gi.courseid = c.id
            AND gi.itemname != 'Attendance'
            AND u.firstname LIKE '%03%'
            AND gi.itemname LIKE '%mative%'
            ORDER BY  `Name` , `Surname` , `Course`, `Assessment` ASC

Name 		Surname		Category 	Module 		Course 		Assessment 	Date 		Competent 	Mark 	
G03 Itumeleng 	Velmah Mokwa 	Fundamentals 	Communications 	CO1 119472 	FORMATIVE 2 	07/04/14 	Yes 		100.00
G03 Itumeleng 	Velmah Mokwa 	Fundamentals 	Communications 	CO1 119472 	SUMMATIVE 	07/04/14 	Yes 		100.00
G03 Itumeleng 	Velmah Mokwa 	Fundamentals 	Communications 	CO2 119457 	FORMATIVE 2 	05/04/14 	Yes 		100.00
G03 Itumeleng 	Velmah Mokwa 	Fundamentals 	Communications 	CO2 119457 	SUMMATIVE 	05/04/14 	Yes 		88.00
G03 Lally 	Sheila Mokane 	Fundamentals 	Communications 	CO1 119472 	FORMATIVE 2 	07/04/14 	NYC 		59.00
G03 Lally 	Sheila Mokane 	Fundamentals 	Communications 	CO1 119472 	SUMMATIVE 	07/04/14 	Yes 		90.00
G03 Lally 	Sheila Mokane 	Fundamentals 	Communications 	CO2 119457 	FORMATIVE 2 	05/04/14 	Yes 		100.00
G03 Lally 	Sheila Mokane 	Fundamentals 	Communications 	CO2 119457 	SUMMATIVE 	05/04/14 	Yes 		98.00

function print_overview_table_groups($COURSE, $choosegroup, $fromdate, $todate, $numarray)
{
    global $DB;
    //check data
    if(!$choosegroup){
        die('No Records To Display.');
    }
   
    $thisgroup = $numarray[$choosegroup];
       
        $sql = "SELECT DISTINCT u.firstname AS 'Name' , u.lastname AS 'Surname', 
			(CASE
			WHEN cc.parent = '2' THEN 'Fundamentals'
			WHEN cc.parent = '3' THEN 'Core'
			WHEN cc.parent = '4' THEN 'Elective'			
			END) AS 'Category',
			cc.name AS 'Module', 
			c.shortname AS 'Course', 
			(CASE
			WHEN gi.itemname LIKE '%summative%' THEN 'SUMMATIVE'
			WHEN gi.itemname LIKE '%formative 2%' THEN 'FORMATIVE 2'
			ELSE 'MC'
			END) AS 'Assessment', from_unixtime(gi.timemodified, '%d/%m/%y') AS 'Date',
			IF (ROUND(gg.finalgrade / gg.rawgrademax * 100 ,2) > 70,'Yes' , 'NYC') AS Competent, ROUND(gg.finalgrade / gg.rawgrademax * 100 ,2) AS 'Mark'
			FROM mdl_course AS c
			JOIN mdl_context AS ctx ON c.id = ctx.instanceid
			JOIN mdl_role_assignments AS ra ON ra.contextid = ctx.id
			JOIN mdl_user AS u ON u.id = ra.userid
			JOIN mdl_grade_grades AS gg ON gg.userid = u.id
			JOIN mdl_grade_items AS gi ON gi.id = gg.itemid
			JOIN mdl_course_categories AS cc ON cc.id = c.category
			WHERE gi.courseid = c.id
			AND gi.itemname != 'Attendance'
			AND u.firstname LIKE '%03%'
			AND gi.itemname LIKE '%mative%'
			ORDER BY  `Name` , `Surname` , `Course`, `Assessment` ASC";

        return $DB->get_records_sql($sql);
   
}

$lists = print_overview_table_groups($COURSE, $choosegroup, $fromdate, $todate, $numarray);
   
	print "<pre>";
	print_r($lists);
	print "</pre>";

Array
(
    [G03 Itumeleng] => stdClass Object
        (
            [name] => G03 Itumeleng
            [surname] => Mokwa
            [category] => Fundamentals
            [module] => Communications
            [course] => CO2 119457
            [assessment] => SUMMATIVE
            [date] => 05/04/14
            [pass] => Yes
            [mark] => 88.00
        )

    [G03 Lally] => stdClass Object
        (
            [name] => G03 Lally
            [surname] => Mokane
            [category] => Fundamentals
            [module] => Communications
            [course] => CO2 119457
            [assessment] => SUMMATIVE
            [date] => 05/04/14
            [pass] => Yes
            [mark] => 98.00
        )

)

<?php
function execInBackground($cmd) {
    if (substr(php_uname(), 0, 7) == "Windows"){
        pclose(popen("start /B ". $cmd, "r"));
    }
    else {
        exec($cmd . "  &> /dev/null &");
    }
}
$command = "java ... ReadEmailsCmdLine 2>&1";
execInBackground($command);

echo "FINALIZADO";