Thanks for your advise.
I´d like see it with an example.
I have other request, it could be for you.....?
I have this code in a lostfocus event in a combolist:

Dialog = 4 + 32 + 256
* 4 = Botones Sí y No
* 32 = Icono del signo de interrogación
* 256 = El segundo botón es el predeterminado
nRec = recno("reclamos")
sele valid_rcl && Copia de Reclamos, utilizada para buscar el valor repetido
locate for thisform.poste.value=poste and thisform.elementos.value=idelemento and thisform.fallas.value=idfalla and estado_act="01" and !recno("valid_rcl")=nRec
if found()
nodefault && To prevent the usual LostFocus from acting
resp =messagebox("El Reclamo que esta Tratando de Agregar, ya esta en la Base de Datos.",Dialog,"Control de Reclamos")
thisform.poste.setfocus()
if resp = 6
thisform.refresh()
endif
endif
This runtime is for validate that new records cannot saved with look on the table if it´s there.
I found ok, but since I add a new combolist, it give up to found, honestly, I don´t know why, I saw the data Dataenvironment and I didn´t find anything.
Eventhough, when I ran the code, the variable called nRec has a negative val, I don´t know why, but acoording to the system the command RECNO return negative numbers for registrations added in a bufer of tables.
I want resolve this problem.
Can your help...?
Andrews