Converted PNG Image from SVG Is Blank

Question

I have one of client has some there own MAP which is coming from map tag into code 

while it binds svg at running time.

 

When I convert SVG to png image is coming blank while my svg has map of selected area.

var svg = document.getElementById('OpenLayers_Layer_Vector_75_svgRoot');
                var xml = new XMLSerializer().serializeToString(svg);
                var data = "data:image/svg+xml;base64," + btoa(xml);
                var img = new Image();

                img.setAttribute('src', data);
                document.body.appendChild(img);