xml using with bulleted list in asp.net

You have to specify the DataTextField & DataValueField properties in your BulletedList:-

<asp:BulletedList ID="BulletedList2" runat="server" BulletStyle="Numbered" 
     DataSourceID="XmlDataSource1" DataTextField="author" DataValueField="year" >
</asp:BulletedList>

Update:

@Michael is correct XmlDataSource does not work with values of xml nodes but only with attributes, so either you will have to modify your XML like this:-

<bookstore>
 <book category="cooking">
  <title lang="en">Everyday Italian</title>
  <author name="Giada De Laurentiis" year="2005"></author>
  <year></year>
  <price>30.00</price>
 </book>
</bookstore>

Then, you will have to specify the XPath attribute like this:-

<asp:XmlDataSource ID="XmlDataSource1" runat="server" DataFile="~/Kategoriler.xml" 
  XPath="/bookstore/book/author"></asp:XmlDataSource>

Then, change your BulletedList attributes accordingly:-

DataTextField="name" DataValueField="year"

But, in reality you probably won't be able to change your XML itself so you can read this XML in code behind and then programmatically bind your BulletedList.

Update 2:

As I said it's not practical to change your XML file according to the XMLDataSource behavior you can alternatively use LINQ-to-XML to query your XML file and bind it like this:-

XDocument xdoc = XDocument.Load(@"YourXMLFilePath");
var XMLdata = xdoc.Descendants("book")
                   //Optional Filter
                   .Where(x => (string)x.Attribute("category") == "cooking") 
                   .Select(x => new
                           {
                              AuthorName = (string)x.Element("author"),
                              Year = (string)x.Element("year")
                           });

Finally, you can bind the data like this:-

BulletedList2.DataSource = XMLdata;
BulletedList2.DataValueField = "Year";
BulletedList2.DataTextField = "AuthorName";
BulletedList2.DataBind();