Notice: Undefined index: sEcho datatable - datatables

Question

I'm having trouble fixing the error Notice: Undefined index: sEcho, I'm using server process script datatable. enter image description here
This is my code of the server_process I'm using:
<?php
/**
* Script: DataTables server-side script for PHP 5.2+ and MySQL 4.1+
* Notes: Based on a script by Allan Jardine that used the old PHP mysql_* functions.
* Rewritten to use the newer object oriented mysqli extension.
* Copyright: 2010 - Allan Jardine (original script)
* 2012 - Kari Söderholm, aka Haprog (updates)
* License: GPL v2 or BSD (3-point)
*/
mb_internal_encoding('UTF-8');
/**
* Array of database columns which should be read and sent back to DataTables. Use a space where
* you want to insert a non-database field (for example a counter or static image)
*/
$aColumns = array( 'id_clien', 'nom_comp_clien', 'exten', 'correo', 'nombre_ofi', 'no_piso', 'id_ofi_c' );
// Indexed column (used for fast and accurate table cardinality)
$sIndexColumn = 'id_clien';
// DB table to use
$sTable = array('clientes' , 'oficinas');
// Database connection information
$gaSql['user'] = 'root';
$gaSql['password'] = '';
$gaSql['db'] = 'sistemacaem';
$gaSql['server'] = 'localhost';
$gaSql['port'] = 3306; // 3306 is the default MySQL port
// Input method (use $_GET, $_POST or $_REQUEST)
$input =& $_GET;
/** * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
* If you just want to use the basic configuration for DataTables with PHP server-side, there is
* no need to edit below this line
*/
/**
* Character set to use for the MySQL connection.
* MySQL will return all strings in this charset to PHP (if the data is stored correctly in the database).
*/
$gaSql['charset'] = 'utf8';
/**
* MySQL connection
*/
$db = new mysqli($gaSql['server'], $gaSql['user'], $gaSql['password'], $gaSql['db'], $gaSql['port']);
if (mysqli_connect_error()) {
die( 'Error connecting to MySQL server (' . mysqli_connect_errno() .') '. mysqli_connect_error() );
}
if (!$db->set_charset($gaSql['charset'])) {
die( 'Error loading character set "'.$gaSql['charset'].'": '.$db->error );
}
/**
* Paging
*/
$sLimit = "";
if ( isset( $input['iDisplayStart'] ) && $input['iDisplayLength'] != '-1' ) {
$sLimit = " LIMIT ".intval( $input['iDisplayStart'] ).", ".intval( $input['iDisplayLength'] );
}
/**
* Ordering
*/
$aOrderingRules = array();
if ( isset( $input['iSortCol_0'] ) ) {
$iSortingCols = intval( $input['iSortingCols'] );
for ( $i=0 ; $i<$iSortingCols ; $i++ ) {
if ( $input[ 'bSortable_'.intval($input['iSortCol_'.$i]) ] == 'true' ) {
$aOrderingRules[] =
"`".$aColumns[ intval( $input['iSortCol_'.$i] ) ]."` "
.($input['sSortDir_'.$i]==='asc' ? 'asc' : 'desc');
}
}
}
if (!empty($aOrderingRules)) {
$sOrder = " ORDER BY ".implode(", ", $aOrderingRules);
} else {
$sOrder = "";
}
/**
* Filtering
* NOTE this does not match the built-in DataTables filtering which does it
* word by word on any field. It's possible to do here, but concerned about efficiency
* on very large tables, and MySQL's regex functionality is very limited
*/
$iColumnCount = count($aColumns);
if ( isset($input['sSearch']) && $input['sSearch'] != "" ) {
$aFilteringRules = array();
for ( $i=0 ; $i<$iColumnCount ; $i++ ) {
if ( isset($input['bSearchable_'.$i]) && $input['bSearchable_'.$i] == 'true' ) {
$aFilteringRules[] = "`".$aColumns[$i]."` LIKE '%".$db->real_escape_string( $input['sSearch'] )."%'";
}
}
if (!empty($aFilteringRules)) {
$aFilteringRules = array('('.implode(" OR ", $aFilteringRules).')');
}
}
// Individual column filtering
for ( $i=0 ; $i<$iColumnCount ; $i++ ) {
if ( isset($input['bSearchable_'.$i]) && $input['bSearchable_'.$i] == 'true' && $input['sSearch_'.$i] != '' ) {
$aFilteringRules[] = "`".$aColumns[$i]."` LIKE '%".$db->real_escape_string($input['sSearch_'.$i])."%'";
}
}
if (!empty($aFilteringRules)) {
$sWhere = " WHERE id_ofi_c = id_ofi ".implode(" AND ", $aFilteringRules);
} else {
$sWhere = "WHERE id_ofi_c = id_ofi ";
}
/**
* SQL queries
* Get data to display
*/
$aQueryColumns = array();
foreach ($aColumns as $col) {
if ($col != ' ') {
$aQueryColumns[] = $col;
}
}
$sQuery = "
SELECT SQL_CALC_FOUND_ROWS `".implode("`, `", $aQueryColumns)."`
FROM `".implode("`, `", $sTable)."`".$sWhere.$sOrder.$sLimit;
$rResult = $db->query( $sQuery ) or die($db->error);
// Data set length after filtering
$sQuery = "SELECT FOUND_ROWS()";
$rResultFilterTotal = $db->query( $sQuery ) or die($db->error);
list($iFilteredTotal) = $rResultFilterTotal->fetch_row();
// Total data set length
$sQuery = "SELECT COUNT(`".$sIndexColumn."`) FROM `".implode("`, `",$sTable)."`";
$rResultTotal = $db->query( $sQuery ) or die($db->error);
list($iTotal) = $rResultTotal->fetch_row();
/**
* Output
*/
$output = array(
"sEcho" => intval($input['sEcho']),
"iTotalRecords" => $iTotal,
"iTotalDisplayRecords" => $iFilteredTotal,
"aaData" => array(),
);
while ( $aRow = $rResult->fetch_assoc() ) {
$row = array();
// for ( $i=0 ; $i<$iColumnCount ; $i++ ) {
// if ( $aColumns[$i] == 'version' ) {
// // Special output formatting for 'version' column
// $row[] = ($aRow[ $aColumns[$i] ]=='0') ? '-' : $aRow[ $aColumns[$i] ];
// } elseif ( $aColumns[$i] != ' ' ) {
// // General output
// $row[] = $aRow[ $aColumns[$i] ];
// }
// }
$row[] = $aRow[ $aColumns[0] ];
$row[] = $aRow[ $aColumns[1] ];
$row[] = $aRow[ $aColumns[2] ];
$row[] = $aRow[ $aColumns[3] ];
$row[] = $aRow[ $aColumns[4] ];
$row[] = $aRow[ $aColumns[5] ];
$row[] = $aRow[ $aColumns[6] ];
$output['aaData'][] = $row;
}
echo json_encode( $output );
?>
I'll be very grateful if somebody could help me out.