.NET Framework :: Parameter Out With Null Value

I am having a trouble when I try to retrieve a SQL parameter outside to .Net Clr

I did a clr example like this:

using System;
using System.Data;
using System.Data.SqlClient;
using System.Data.SqlTypes;
using System.Text;
using Microsoft.SqlServer.Server;

[Code] ...

I now my trouble and it is because the parameter @p_it is null when I try to sed it to pipe in SqlContex but really it is not null. When I test the clr with this code:

CREATE ASSEMBLY
[Test]
FROM
N'Z:SomeRouteTest.dll'
WITH PERMISSION_SET = SAFE
GO
CREATE PROCEDURE [dbo].[Test]

[Code] ....

I obtain the next error message:

"Mens 6522, Nivel 16, Estado 1, Procedimiento Test, Línea 14
A .NET Framework error occurred during execution of user-defined routine or aggregate "Test":
System.ArgumentNullException: El valor no puede ser nulo. -----> The value can not be null
Nombre del parámetro: message
System.ArgumentNullException:
   en Microsoft.SqlServer.Server.SqlPipe.Send(String message)
   en Test.StoredProcedures.Test(SqlString p_t)"