make 2 xsd file from xml

Question

hi
i have 2 xml file:Orders.xml , OrderDetails.xml
i want to make 2 xsd file from them with this code :

DataSet ds = new DataSet();

            ds.ReadXml("Orders.xml");
            ds.WriteXmlSchema("Orders.xsd");


            DataSet ds2 = new DataSet();

            ds2.ReadXml("OrderDetails.xml");
            ds2.WriteXmlSchema("OrderDetails.xsd");

but when i want run program,i face 17 Error!
one of them is :
Error    1    The type 'WindowsFormsApplication1.DocumentElement' already contains a definition for '_schemaSerializationMode'   

Error    2    Type 'WindowsFormsApplication1.DocumentElement' already defines a member called 'DocumentElement' with the same parameter types   

Error    3    Type 'WindowsFormsApplication1.DocumentElement' already defines a member called 'DocumentElement' with the same parameter types 

and .......
please help me