FoxPro/Visual FoxPro - Problemas con Form

hola amigos del foro les escribo porque tengo un problema q no puedo resolver en un formulario de carga de medicamentos pasa lo siguiente: cuando tengo la tabla de medicamento vacia el pageframe no me habilita el campo para ingresar el codigo de medicamento pero si x lo menos tengo un registro en blanco ocurre lo contrario alguien me podria decir q pasa, tengo la siguente rutina dentro del form en activate event:

sele medins
ThisForm.Pageframe1.Page1.Txtcodmein.value=0
ThisForm.Pageframe1.Page1.Txtdesmein.value=space(60)
ThisForm.Pageframe1.Page1.Txttippre.value=space(1)
ThisForm.Pageframe1.Page1.Txtcodpre.value=0
ThisForm.Pageframe1.Page1.Txtdespre.value=space(25)
ThisForm.Pageframe1.Page1.Txtpreuni.value=0
ThisForm.Pageframe1.Page1.Txtprebul.value=0
ThisForm.Pageframe1.Page1.Txtstomin.value=0
ThisForm.Pageframe1.Page1.Txtstock.value=0
ThisForm.Pageframe1.Page1.Txtstobul.value=0
ThisForm.Pageframe1.Page1.Txtfecalt.value=0
ThisForm.Pageframe1.Page1.Txtfeven.value=0
ThisForm.Pageframe1.Page1.Txtfeulin.value=0
ThisForm.Pageframe1.Page1.Txtfeuleg.value=0
ThisForm.Pageframe1.Page1.Txtcodmar.value=0
ThisForm.Pageframe1.Page1.Txtdesmar.value=space(20)
ThisForm.Pageframe1.Page1.Txtcodpro.value=0
ThisForm.Pageframe1.Page1.Txtnompro.value=space(40)
ThisForm.Pageframe1.Page1.edtobser.value=space(10)
ThisForm.Pageframe1.Page1.Txtdesmein.enabled=.f.
ThisForm.Pageframe1.Page1.Txttippre.enabled=.f.
ThisForm.Pageframe1.Page1.Txtcodpre.enabled=.f.
ThisForm.Pageframe1.Page1.Txtdespre.enabled=.f.
ThisForm.Pageframe1.Page1.Txtpreuni.enabled=.f.
ThisForm.Pageframe1.Page1.Txtprebul.enabled=.f.
ThisForm.Pageframe1.Page1.Txtstomin.enabled=.f.
ThisForm.Pageframe1.Page1.Txtstock.enabled=.f.
ThisForm.Pageframe1.Page1.Txtstobul.enabled=.f.
ThisForm.Pageframe1.Page1.Txtfecalt.enabled=.f.
ThisForm.Pageframe1.Page1.Txtfeven.enabled=.f.
ThisForm.Pageframe1.Page1.Txtfeulin.enabled=.f.
ThisForm.Pageframe1.Page1.Txtfeuleg.enabled=.f.
ThisForm.Pageframe1.Page1.Txtcodmar.enabled=.f.
ThisForm.Pageframe1.Page1.Txtdesmar.enabled=.f.
ThisForm.Pageframe1.Page1.Txtcodpro.enabled=.f.
ThisForm.Pageframe1.Page1.Txtnompro.enabled=.f.
ThisForm.Pageframe1.Page1.edtobser.enabled=.f.
ThisForm.Pageframe1.Page3.enabled=.f.
ThisForm.Pageframe1.Page1.commandgroup1.command1.enabled=.f.
ThisForm.Pageframe1.Page1.commandgroup1.command2.enabled=.f.
ThisForm.Pageframe1.Page1.commandgroup1.command3.enabled=.f.
ThisForm.Pageframe1.Page1.commandgroup1.command4.enabled=.f.
ThisForm.Pageframe1.Page1.commandgroup1.command5.enabled=.f.
ThisForm.Pageframe1.Page1.commandgroup1.command6.enabled=.f.
ThisForm.Pageframe1.Page1.commandgroup2.command1.enabled=.f.
ThisForm.Pageframe1.Page1.commandgroup2.command2.enabled=.f.
ThisForm.Pageframe1.Page1.commandgroup2.command3.enabled=.f.
ThisForm.Pageframe1.Page1.commandgroup2.command4.enabled=.f.
ThisForm.Pageframe1.Page1.Txtcodmein.setfocus

es asi
debes de tener en el controlsource del objeto el campo de la tabla y como esta vacia no te lo habilita
tenes que sacar el conterolsource y asignarlo al objeto por programa
cuando es modificacion le pones el controlsourec con es un alta, lo dejas vacio

muchas gracias sergio por tu aporte ya pude resolver el inconveniente nos vemos en cualquier momento