I have made a mess

I am working to make my on mod and now in all my games i cannot build a horse breeder any more. I have made some changes in the factions, I have installed the byzantyne light cavalry addon and make avaliable the alan cavalry to the byz as drafted unit and the Armenian Cavalry to all the factions. Nothing more

Any idea about what could be happened ?

Thanks a lot

id start in the build file, check and make sure all the data is good, and no missing field. hopefully you made a back up of it to cross reference, without seeing the files, i wouldnt know where else to begin.