I would recommend running the debugger on your code and isolate the exact line of code the error occurs on. I would also recommend stripping out all other controls to isolate the exact problem. You may have related issues that are masking what is going on. Create a brand new form that uses a textbox and add functionality to it, testing each time new code is added.

>Cathi:
>
>Here we go again. The null problem disapear after I move the declaration after the asignment of space(1) to the column "Num_control" using the code sample that you show me long time ago.
>
>But now I got another unexplain message that maybe you saw it already and have the reason for that, the following message was displayed
>
>---------------------------
>
>---------------------------
>Can't bind to property or column num_control on DataSource.
>
>Parameter name: dataMember
>---------------------------
>OK
>---------------------------
>
>The Subroutine with problem is here
>
>Private Sub ENTREVISTA_INITIAL_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
> AddHandler Riesgo_DataGrid1.MouseUp, AddressOf Riesgo_datagrid1_mouseup
> AddHandler Off_site_DataGrid1.MouseUp, AddressOf Off_site_DataGrid1_MouseUp
>
> 'AddHandler Socio_Econo_grid.CurrentCellChanged, AddressOf Socio_Econo_grid_currentcellchanged
>
> Try
> 'Attempt to load the dataset.
> Me.LoadDataSet()
> Me.LoadDataset4()
> Me.BindingContext(ObjDatos_personales_sol1, "Datos_personales_sol").EndCurrentEdit()
> dr = ObjDatos_personales_sol1.Tables(0).NewRow()
> dr(0) = Space(1)
> dr(3) = Space(1)
> dr(4) = Space(1)
>
> ObjDatos_personales_sol1.Tables(0).Rows.Add(dr)
>
> Me.BindingContext(ObjDatos_personales_sol1, "Datos_personales_sol").Position = ObjDatos_personales_sol1.Tables(0).Rows.Count - 1
> Dim SocSecNum As New Binding("Text", ObjDatos_personales_sol1, "num_control")
> AddHandler SocSecNum.Format, AddressOf Me.TextBox2_FormatSS
> AddHandler SocSecNum.Parse, AddressOf Me.TextBox2_DrafSS
> TextBox2.DataBindings.Add(SocSecNum)
>
> I = 0
> Catch eLoad As System.Exception
> 'Add your error handling code here.
> 'Display error message, if any.
> MessageBox.Show(eLoad.Message)
>
> End Try
> End Sub