It isn't that there is this "true root cause" that created the current problem. There is a way to look at the issue and find a deeper cause that will allow you to address it and improve the future performance of the system.
Depending on how you look at the problem there can be many different "root causes" that are sensible from their different perspectives. The important thing is by aiming to fix root/systemic problems you will not just treat the current symptom you are dealing with today but eliminate future problems from occurring.
continue reading: Root Cause - Addressing Systemic Causes Not Symptoms