US Scott 1359 Tagging

I (maybe) have a weird Scot 1359 - Lief Erickson Issue - that appears to have no tagging. No matter how dark the room is, I can't get it to fluoresce under my blacklight. According to Stamp Smarter, the tagging on this is "Phosphored ink - tagging mixed with ink (Added to Color")". Has anyone run into this before? Is it possible that I've got a stamp in which they ran out of the additive before printing. I'd attach a scan of the stamp, but, unfortunately, I don't have the capability to scan under my blacklight. In addition, if I could, I'm not sure what it would show - a dark stamp? Thanks,

Alan

Is it a mint or used stamp? You have to be very careful with used examples.

Note that you don't have to give us a scan of this issue. Take your backlight over the stamp, and then take a picture with your cell phone. Upload that so that we can see. Best idea is to show the backlight over your stamp and another which successfully shows the tagging.

The taggant is mixed into the light brown color. So the stamp should glow greenish (365nm longwave uv) in the background and the left half of the statue. Color misregistrations are known so the actual areas of glow might be sightly "weird".

Single from corner of a pane:
Normal light and short-wave UV light, although not a good exposure: