you should have mentioned, that the person must have MOVED in this period - otherwise it's logical that he/she is missing. 90-95 % of all cards exist!
Regards Andre Munich
snip......Last summer we learned of the existence of images of the residence registration index cards >from the city of Posen/Poznan.
The date range for these cards is given as 1870-1931. They are of great interest because they list all the members of a family and give birth dates and places--and sometimes the names of parents too. Moves, both within Posen/Poznan and from/to the city are noted. snip........