Golf gti 8 v won't start please help

[Army1619]

Need some help got a golf mk3 2lt 8 v .cant get it to start when you turn the ignition on no dash lights come on you can turn the car over it will start for 2 seconds the cut out put it on vag-com says immobiliser stopped engine I have changed the ecu ,immobiliser ,ignition switch ,ecu relay and fuel pump relay please can some one give me some idea as I am now stuck .with the new second hand ecu it still comes up with the same fault 

[sharki786]

Did you change the brown ring that goes around the ignition barrel (dont know what its called) also did you get the chip from the key? Transponder or something like that

[itavaltalainen]

brown thing is probably called a receiver coil. do you have a second set of keys for original ecu?
did you get keys with the new control units?

if you still got a working one you could transplant transponders to your keys and then teach them to ecu.