How to display the info window just above the polyline in Google Map?

The problem is that I take information about latitude and longitude from the database and draw polylines on a Google map using the Info Window, it worked fine with markers. However, an info window appears on top of the Google map, although I set its position. I used the code as follows: -

 <script type="text/javascript">


 function initialize()
        {
          var map;

           var markers = JSON.parse('<%=ConvertDataTabletoString() %>');
     var infoWindow = new google.maps.InfoWindow({maxWidth:200,minWidth:200});
           var marker;

           var x=new google.maps.LatLng(16.697000,74.244000);
       var stavanger=new google.maps.LatLng(markers[0].lat1, markers[0].lng1);

         var london=new google.maps.LatLng(markers[0].lat, markers[0].lng);
           var j=0;

           var i=0;
           var points=new Array();
           var points2=new Array();

           var mapProp = {
           center:new google.maps.LatLng(markers[0].lat, markers[0].lng),
           zoom:14,
           mapTypeId:google.maps.MapTypeId.ROADMAP

            }; 
   var map=new google.maps.Map(document.getElementById("map_canvas"),mapProp);

             google.maps.event.addListener(map, "click", function(event)
        {

                var marker = new google.maps.Marker({
                position: event.latLng, 
                 animation: google.maps.Animation.DROP,
                map: map

                });


              document.getElementById("txttolat").value = event.latLng.lat();
             document.getElementById("txttolong").value = event.latLng.lng();

               var pt=event.latLng.lat();
             points[j]=event.latLng.lat();

             points2[j]=event.latLng.lng();
             j=j+1;

              document.getElementById("txtlat").value = points[0];
             document.getElementById("txtlong").value = points2[0];
             //            });

              });

             for (i = 0; i < markers.length; i++) {
             var data = markers[i]

    var stavanger2=new google.maps.LatLng(markers[i].lat1, markers[i].lng1);

         var london2=new google.maps.LatLng(markers[i].lat, markers[i].lng);

              var myTrip=[stavanger2,london2];
               var flightPath=new google.maps.Polyline({




                path:myTrip,
            strokeColor:"#0000FF",
             strokeOpacity:0.8,
             strokeWeight:10,
               map: map,
               title: data.title
                    });
                  // }
                  (function(flightPath, data) {

           google.maps.event.addListener(flightPath, 'click', function(e) {
                 // alert('you clicked polyline');

               infoWindow.setContent(data.description);

                 infoWindow.open(map,flightPath);
                 infoWindow.setPosition(e.latLng);
                 document.getElementById("txtname").value = data.title;

                  document.getElementById("txtlat").value = e.latLng.lat();
                  document.getElementById("txtlong").value = e.latLng.lng();
                     });

                      })(flightPath, data);


                       }
                       }



               google.maps.event.addDomListener(window, 'load', initialize);
                    </script>