getBBox problem

HTML

<embed class="svg-img" id="svg1"...

JavaScript

function getSubDocument(embedding_element)
		{
			if (embedding_element.contentDocument) 
			{
				return embedding_element.contentDocument;
			} 
			else 
			{
				var subdoc = null;
				try {
					subdoc = embedding_element.getSVGDocument();
				} catch(e) {}
				return subdoc;
			}
		}
				

var elms = document.querySelectorAll(".svg-img");
for (var i = 0; i < elms.length; i++)
{
	console.log(elms[i]);
  var subdoc = getSubDocument(elms[i])
  console.log(subdoc);
}