Using XML Namespace in Script Functoid

Hi

I have created a simple map which consist of Script Functoid.

In that Functoid i have written Inline C# code as

"System.XML.XmlDocument xdoc = new System.XML.XmlDocument();

xdoc.LoadXml(strxml);"

When I build this project i faced following error…

"Inline Script error: The type or namespace name 'xdoc' could not be found (are you missing a using directive or an assembly reference)"

But project already consist of reference for System.XML directive.

then also why that error occured?

Thanks