LDD bricks with knobs

[THERIZE]

I'm building a SD40 In LDD but i can't put plates on bricks with knobs on the side? I'm sure its possible but i don't know why and I searched for tutorials on youtube but i can't find answers there. Im pretty new to LDD and i only know the basics. I hope someone can help me.

[Calabar]

Could you provide a screenshot? (CTRL+K in LDD, maybe enabling advanced graphics)