Having issues placing candy in the display

You can either drag the candy in live mode, from where it is placed, into the display case. Or have the candy in the inventory of your sim, click on the display case, choose stock surface, then choose the candy from your sims inventory. Are you having issues doing this? 

I have tried moving it in live mode and build mode and it won’t place, but I haven’t tried stocking the surface by clicking on the display.  I will try this next time, thank you