...
Set grdDatos.DataSource = Nothing <- i clear the data grid
Set grdDatos.DataSource = ObjSiap.ObjContribs.DarListaContribuyentes(True, True, ObjConfi.bOrdenLC, ObjConfi.sNumColLC) <- this method return a recordset.. it's on a dll
grdDatos.Refresh <- another try to fix the problem

Public Function DarListaContribuyentes(bPf As Boolean, bPj As Boolean, bAsc As Boolean, sTipo As String) As ADODB.Recordset
    Dim Rs As ADODB.Recordset
    Set Rs = New ADODB.Recordset
    Dim sSql As String
    sSql = ""
    If bPf And bPj Then
        sSql = " "
    ElseIf bPf Then
        sSql = " WHERE tipopersona = 0"
    ElseIf bPj Then
        sSql = " WHERE tipopersona = 1"
    End If
    If StrComp(UCase$(sTipo), "C") = 0 Then
        sSql = sSql & " ORDER BY cuit"
    Else
        sSql = sSql & " ORDER BY descrip"
    End If
    If Not bAsc Then
        sSql = sSql & " DESC"
    End If
    Rs.CursorLocation = adUseClient
    Rs.Open "SELECT CUIT,DESCRIP from contribs" & sSql, ClaseBase_ConexionBD, adOpenStatic
    Set DarListaContribuyentes = Rs
    Set Rs = Nothing
End Function