problem with generating xps document

Question

i want to create a virtual printer,then get data from virtual printer and process data

i use Passthrough XPS driver to get data in xps type

then i install redmon to redirect the virtual printer to my c# program

my c# program get data and save it in a file,but i can't open file with xps viewer

this is my c# code

static void Main()
{
string fname = Environment.GetEnvironmentVariable("TEMP") + @"\";
fname += "1.xps";
FileStream fs = new FileStream(fname, FileMode.Create);
StreamWriter sw = new StreamWriter(fs);
StreamReader sr = new StreamReader(Console.OpenStandardInput());
sw.Write(sr.ReadToEnd());
sw.Flush();
sw.Close();
sr.Close();
}
thanks