S4r tachometer not working

I am new to this forum! I have a 2005 S4R and my tachometer isn't working. I replaced the entire gauge cluster with a new one and still it doesn't work! Both needles does the initial sweep when I turn on the bike but then the tach will not read the rpms. Any clues? Bad Coils? The bike seems to run fine but it just won't read the rpms. This was also the case even with the old gauge cluster.