Hi - I assume your 28 Elmarit brings up the 28mm framelines? It would be very odd if it didn't, but it is necessary for this to be correct along with the 6-bit code for the M8 to recognize the lens. Using the coder kit template, it's pretty hard to get the code backwards, but not hard to ink in a code that's not recognized. The black dots have to be sizable and dark, and not glossy (a reflection from a shiny dot could be read as white/blank). Fortunately, you have only two black dots, and they're right next to each other; should be pretty error-free with flat-black paint. Here are the codes for the various 28 Elmarits (1 is black, 0 is white, and the order assumes you're looking at the rear of the lens with it rotated so the coding is at top):
Elmarit-M 28mm f/2.8 (III) 11804; coding is 000011
Elmarit-M 28mm f/2.8 (IV) 11809; coding is 011011
Elmarit-M 28mm f/2.8 ASPH. 11606; coding is 011100 also suggested for Zeiss Biogon T* 2.8/28 ZM, Konica M-Hexanon 28mm f/2.8
There IS a similar 90mm coding... if when coding 000011 you got your left black dot too wide or too far to the left it might be picked up this way:
Summicron-M 90mm f/2 (II) 11136, 11137 coding is 000111
This would be valid because 90mm and 28mm share the same frameline set.