encode ออกมาเป็น JSON ไม่ได้ครับ รบกวนผู้รู้ช่วยทีครับ

<?php
	$objConnect = mysqli_connect("localhost","root","");
	$objDB = mysqli_select_db("webappdb");
	
	// $_POST["txtKeyword"] = "a"; // for Sample

	$strKeyword = $_POST["txtKeyword"];
	$strSQL = "SELECT * FROM member WHERE 1 AND Name LIKE '%".$strKeyword."%'  ORDER BY MemberID ASC  ";

	$objQuery = mysqli_query($strSQL);
	$intNumField = mysqli_num_fields($objQuery);
	$resultArray = array();
	$arrCol = array();
	while($obResult = mysqli_fetch_array($objQuery))
	{
		for($i=0;$i<$intNumField;$i++)
		{
			$arrCol[mysqli_field_name($objQuery,$i)] = $obResult[$i];
		}
		array_push($resultArray,$arrCol);
	}
	
	mysqli_close($objConnect);
	
	echo json_encode($resultArray);
?>