Sebastian,

>I try to insert a new record in a base SQL Server 2005, being still the guide.
>
>In the page_load Event:
>
> Me.oOrigen = CType(Me.RegisterBizObj(New Origen), Origen)
> Me.IdOrigen = Integer.Parse(Request.QueryString("IdOrigen"))
>
> Me.oOrigen.OrigenGetByID(Me.IdOrigen)
> Session("dsOrigen") = oOrigen.DataSet
>
>To insert:
>
> Dim ds As DataSet = CType(Session("dsOrigen"), DataSet)
>
> Me.oOrigen.NewRow(ds, Me.oOrigen.TableName)
>
> Session("ds") = dsOrigen
>
>To Save:
>
> Dim ds As DataSet = CTyThpe(Session("dsOrigen"), DataSet)
>
> If Me.Save(Me.oOrigen, ds, Me.oOrigen.TableName) = mmSaveDataResult.RulesPassed Then
> Response.Redirect("OrigenCrud.aspx")
> End If
>
>Display that error:
>
> System.NullReferenceException was unhandled by user code
> Message="Referencia a objeto no establecida como instancia de un objeto."
> Source="OakLeaf.MM2008.Framework"
>
>
>Thank for your time
>
>...Saludos Amigo...

Is all of this code in the Load Event or are you trying to save from a button or something? Since the error indicates a reference to an object that has not been instantiated; in the web environment it is important to keep track of the post backs and what is available. Can you post where these code pieces are in your form.
Thanks
Tim