clio imobiliser?

i have a 1999 1400 clio . i was told the ecu was blown as it would not send a signal to give a spark..all other systems were fine.. so i got a second hand ecu plus the ign lock with the key and the reader that fits around the ign lock.. still no spark// now the imobiliser light on the dash flashes like mad as well.. does anyone know if there is another part that i should have got of the same doner car to complete the job////also i have notised that the key i got with the ing lock wen i press the button the little ilght on it does not light up// i have checked the batteries they seem ok 5.9 volt .. any help please...den