Xailer forum

In init modul I have
::oBRW:aCols[3]:OnEdit := "UzmiSifru"
METHOD UzmiSifru( oSender, oPrevCtl ) CLASS TPrijemZ
LOCAL oRS := TBChoice( "SELECT Naziv, Sifra, Code, VPCena, MPCena, JMere
FROM Sifre", "Izbor artikla" )
LOCAL nSifra := IF( VALTYPE(oRS)=="N", 0, oRS:Sifra )
IF nSifra == 0
oRS := TNoviArtikal():New()
oRS:ShowModal()
ELSE
oSender:oDataField:VarPut( nSifra )
oSender:Refresh()
msgbox( str(nSifra)+oSender:oDataField:cName )
ENDIF
RETURN .T.
Why I can't change value in cell?