Google Marker

Quando clikco não cria o mark… alguem me ajuda?

< button onclick="TestMarker();" class="btn"><img src="img/ico.ico"/>Localizar < /button>

<script>
            var latitude = -14.6915082;
            var longitude = -60.0014007;
            var zoomap = 4;
            
            function initMap() {
                var myLatLng = {lat: latitude, lng: longitude};
                var map = new google.maps.Map(document.getElementById('map'), {
                    zoom: zoomap,
                    center: myLatLng
                });
            }
            
            function TestMarker() {
                Busca = new google.maps.LatLng(-14.6915082, -60.0014007);
                addMarker(Busca);
            }
            
            function addMarker(location) {
                marker = new google.maps.Marker({
                    position: location,
                    map: map
                });            
            }
            
            function deleteMarkers() {
              clearMarkers();
              markers = [];
            }
</script>