You may wish to review this article as well.
Let's take the example below where N/A @ 1300 nm appears at the launch event (patch panel).
This is normally followed by WARNING as the summary test result. So what causes the N/A? To understand why the OptiFiber reported N/A, we need to look at the 1300 nm trace (shown below):
The clue was in the event table @ 850 nm where the loss was 0,61 dB. Within the allowed 0,75 dB but not a great connection, suggesting that this mated connection is less than perfect. Now look to the 1300 nm trace (green). The reflection is much higher and wider - a definite indication of an issue at this location. The 1300 nm trace does not recover in time before the end event. If the trace does not recover before the next event (the end event as in this case), OptiFiber is unable to establish the loss and reports N/A. This is the case for all OTDRs.
You should inspect the end faces with a fiber scope. A common cause of this "tailing" at 1300 nm is the use of Isopropyl alcohol (IPA) that is less than 98% proof. Take a quick look at the bottle of IPA you are using to see the % proof. For instance, rubbing alcohol is typically 78 % and of course should not be used - even if it is conveniently available at your local food store.
What should you expect?
When cleaned and polished well, you should see a trace similar to the green trace above.