Block IDs are not working all

Hello

Wen i am doind a build in creative and i use id 43:6 or other ids like this they give me other block wen i place it

Example i have id 43:6 in my inventory and want to place it. i get id 43 duoble step. not the on it should be.
the blocks that where placed before are unchanged. i can also spawn those items using worldedit.
can you guys please fix this. its pretty anoying!

best regards Andy