whats up guys!

some days ago, i want install a typeR tachometer on my friend's Eclipse, its RS 97

I put the + wire in a fuse on fuse box inside the car, i use a tester and find a fuse that work's with the ign switch.
The wire of light i leave this un-connect because the light of tach doesn't work lol
The ground wire in the steel of console
the rpm signal wire, i put this on the white wire on the ECU. but...

The tach doesn't work!!

what can i do?

i search but all thread says the same thing "rpm signal wire: white wire of lower harness"

Help me please!!