Remember for infini key to work the PCB must be able to receive said key, any failure in that and of course its not going to work.
Aka this isn't an issue with Infini Key, but and issue with your B-board.
|Darksoft/Apocalypse: CPS2, CPS3, F3-β, MVS, S16-β|
Marqs: OSSC v1.5/1.6 VGP, OSSC v1.6 Kaico
invzim: Jammafier v1.6b/1.7c, Tri-Sync Helper, JVSPAC2
XianXi: JNX Raiden, SC Taito Classic, SC Sega S16/24, Namco S11/12 KHA
Frank_fjs: JAMMA Extender SE-HAS, Jassifier v1.6