WriteXml() Question

Hi

Can anyone tell me how to generate an XML file using a typed dataset?
I have a typed dataset called _WorkStationDataSet. But WriteXml() can not be called direclty from it, I have to create a new instance of it using:
_WorkStationDataSet ds = new _WorkStationDataSet(), but then calling WriteXml() on ds does not create a hierarchical xml file, instead it just puts two lines of xml at the top of the file showing the name of the dataset.

How do i call WriteXml() on a Strongly Typed Dataset? Please Help