dataset.writexml - xmlns:dt

Question

I read an xml file into dataset with ReadXml method.
then i update the data on one of the datatables. next
I write the dataset to a file using
.WriteXml(strFilePath + strFilename,XmlWriteMode.IgnoreSchema)

The updated xml creat with the updated data but I get the xmlns:z="#RowsetSchema" in the node.

How can I get the updated xml without the xmlns ?