This decoder's algorithm was hand-programmed by Just Rickenbackers and works reliably compared to many other decoders on the internet. All serial numbers from Rickenbacker guitars and basses since 1954 should retrieve some sort of result. Keep in mind that just because you type in something, doesn't mean it exists; it only confirms the information embedded within a serial number if it is indeed a real serial number. The algorithm uses logic and based on patterns from various sources over the years. If you are uncertain still about your situation use the Contact link on the website to get hold of us.