Почему некоректно отображаются карты Google Map?

<div id="map_canvas" style="width: 800px; height: 100%;"></div>

function initialize_map( ) {
     var latlng = new google.maps.LatLng(49.25100320801442,28.541126489672024);
     var myOptions = {
     zoom: 18,
     center: latlng,
     mapTypeId: google.maps.MapTypeId.ROADMAP
     };
    var map = new google.maps.Map(document.getElementById("map_canvas"), myOptions);
    var polygonCoords = [
   	  new google.maps.LatLng(49.25156346163994,28.542151093515713),
   	  new google.maps.LatLng(49.25113626882619,28.542376399072964),
   	  new google.maps.LatLng(49.25074759018555,28.541657567056973),
   	  new google.maps.LatLng(49.25076509829823,28.54119622710641),
   	  new google.maps.LatLng(49.25100320801442,28.541126489672024)
   	 ];
   	 var polygon = new google.maps.Polygon({
   	  path: polygonCoords,
   	  strokeColor: "#5196DB",
   	  strokeOpacity: 1,
   	  strokeWeight: 2,
   	  fillColor: "#8ab9e7",
   	  fillOpacity: 0.5
   	 });
   	 polygon.setMap(map);   
   	 return map;
   }

#modal_form {
  	width: 800px;
  	height: 800px;
  	background: #fff;
  	position: absolute;
  	z-index: 5;
  	padding: 0px 0px;
  	padding-top:45px;
  	bottom:40px;
  	top: 80px;
  	margin-left: 30%;
}
#modal_form #modal_close {
	width: 21px;
	height: 21px;
	position: absolute;
	top: 10px;
	right: 10px;
	cursor: pointer;
	display: block;
}