ODP.NET :: Nested Cursor From Stored Procedure

I'm trying to fetch data from Ref Cursor OUT parameter filling by stored procedure. Using latest version of ODP.NET provider (11.2.0.3.0).

My stored procedure:

TYPE cursor_type IS REF CURSOR;

PROCEDURE test_proc (p_recordset out cursor_type) AS
BEGIN
OPEN p_recordset FOR
SELECT 1,2, CURSOR (SELECT 3,4 FROM dual)
FROM dual
END;
END test_proc;

If i'm removing "*CURSOR (SELECT 3,4 FROM dual)*" from the procedure, all works just fine. But when the nested cursor exists in procedure, i'm getting the following exception:

System.NullReferenceException occurred
Message=Object reference not set to an instance of an object.
Source=Oracle.DataAccess
StackTrace:
at Oracle.DataAccess.Client.OracleDataReader.GetOraDbTypeEx(Int32 i)
[code]........

My c# code:

using (OracleConnection conn = new OracleConnection(connString))
*{*
OracleCommand command = new OracleCommand();
command.Connection = conn;
command.CommandType = System.Data.CommandType.StoredProcedure;
command.CommandText = "test_proc";
[code].......

If i'm changing procedure signature from out parameter, to return value, code throws the same exception.