Calling Oracle Stored Procedure. Getting 'No Data Found' Exception

I'm trying to call an Oracle Stored Procedure which returns XMLType data, but all I receive is a 'No Data Found Exception'. The table has data. I have checked that, and then double checked. Is there something wrong in my code that calls the stored procedure. Maybe something obvious, I am completely missing.

using (OracleConnection dbc = new OracleConnection("Data Source=test; User ID=user; Password=pwd"))
{
   dbc.Open();
   using (DbTransaction trans = dbc.BeginTransaction())
   {
      try
      {
         DbCommand comm = dbc.CreateCommand();
         comm.CommandType = CommandType.StoredProcedure;
         comm.CommandText = "TestStoredProcedure";
         comm.Transaction = trans;

         OracleParameter returnParam = new OracleParameter("result", OracleDbType.XmlType);
         returnParam.Direction = ParameterDirection.ReturnValue;
         comm.Parameters.Add(returnParam);

         OracleParameter param1 = new OracleParameter("param1", OracleDbType.Varchar2);
         param1.Direction = ParameterDirection.Input;
         param1.Size = 70;
         param1.Value = "testing";
         comm.Parameters.Add(param1);

         OracleParameter param2 = new OracleParameter("param2", OracleDbType.Varchar2);
         param1.Direction = ParameterDirection.Input;
         param1.Size = 70;
         param1.Value = "testing";
         comm.Parameters.Add(param2);

         OracleParameter param3 = new OracleParameter("param3", OracleDbType.Date);
         param1.Direction = ParameterDirection.Input;
         param1.Value = Convert.ToDateTime("1/18/2011 12:00:00 AM");
         comm.Parameters.Add(param3);

         comm.ExecuteNonQuery(); //exception at this line

         OracleXmlType oracleXml = (OracleXmlType)comm.Parameters["result"].Value;
         XmlDocument xmlDoc = oracleXml.GetXmlDocument();
      }
      catch (Exception ex)
      {
          Console.WriteLine(ex.ToString());
      }
   }
}

The stored procedure:

declare
  -- Non-scalar parameters requir开发者_开发百科e additional processing 
  result sys.xmltype;
begin
  -- Call the function
  result := mktadmin.test_package.test(param1 => :testval1,
                                       param2 => :testval2,
                                       param3 => :testval3);
end;

EDIT: Ignore any discrepancy in names. I had to edit them to post here.

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Looks like you are overwriting param1 properties in the param2 and param3 section assignments.

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It would be useful to see the stored procedure. You usually get the no data found error when doing a select into that yields no results.