LINQ to XML in C# error?

// This returns AccessViolationException. There is an element named "account" with the attributes "title" and "uname" set, according to http://msdn.microsoft.com/en-us/library/bb348975(v=vs.110).aspx it should work!?

// Sample XML content
// <xml>
// <settings>
//    <setting name="test" value="value"/>
// </settings>
// <accounts>
//    <account title="test" uname="testname"/>
// </accounts>
// </xml>

IEnumerable<XElement> tmpSettings = null;
IEnumerable<XElement> tmpAccounts = null;
try
{
   tmpSettings = from el in XMLData.Elements("setting")
                 select el;
   System.Diagnostics.Debug.WriteLine("Node name: " + tmpSettings.FirstOrDefault().Attribute("name").Value);
   System.Diagnostics.Debug.WriteLine("Node value: " + tmpSettings.FirstOrDefault().Attribute("value").Value);
   tmpAccounts = from el in XMLData.Elements("account")
                 select el;
   System.Diagnostics.Debug.WriteLine("Node name: " + tmpAccounts.FirstOrDefault().Attribute("title").Value);
   System.Diagnostics.Debug.WriteLine("Node value: " + tmpAccounts.FirstOrDefault().Attribute("uname").Value);
}catch(Exception ex)
{
   //do nothing
}