Diaphragm disabled

Hello, I'm trying to model diaphragms but the option is disabled, what should I do? I had diaphragms in my bridge, but those were not following my deck slope, so I deleted them, but cant add those anymore. I saw that the OBM 2021 realease 2 have this diaphragm option, so maybe I with the wrong version? Where can I see the version I'm currently working with? 

Thanks