mysql query does not work with where clause and variable

Question

i'm trying to get data from table using mysql where clause. but it does not return any value or error.

here is the function

function getMsgByName($sender){
        global $connection;
        $sender  = mysqli_real_escape_string($connection,$sender);

        $query = "SELECT Message FROM chat WHERE Sender ='$sender'";
        $run = mysqli_query($connection,$query);
        $messages = array();
        while($message = mysqli_fetch_assoc($run)){
            $messages[] = array('message'=>$message['Message']);
        }
        return $messages;

    }