I cannot place blocks, entities, or tile entities. (stone, pig, head)

I cannot place blocks or spawn mobs.
I cant do anything!
I tried this but nothing happened...
I expected it to place a block or spawn a mob.
It didnt do anything. I can only destroy blocks and attack mobs.
Plz help...
It wouldnt place blocks or mobs or name them. Only would work with /fill, /setblock, /summon, or /entitydata.
But I cant use those commands just to replace right-click!
1.Go to minecraft 1.8
2.Go into your world and place a block or use spawn eggs
3.If you have at least two accounts on your PC/Mac, (not Minecraft)
log onto both and go to edit profile, then select: "use latest version". Unfortunatley it STILL wont work 😞