command blocks don't work with code to give things

Hi. I am playing on a vanilla server. I alternate between 1.12 and snapshot 18w16a. I play single player. normal realm. I play in creative mode and I cannot use command blocks to give me things. I can use a command block to say things like "hello" but I cannot use code to give me things like custom banners or custom heads from various webpages..

i.e if I post a code like: /give @p skull 1 3 {display:

{Name:"Speaker"}

,SkullOwner:{Id:"a33c6009-813a-469e-9ecc-53b8ac042303",Properties:{textures:[

{Value:"eyJ0ZXh0dXJlcyI6eyJTS0lOIjp7InVybCI6Imh0dHA6Ly90ZXh0dXJlcy5taW5lY3JhZnQubmV0L3RleHR1cmUvNzJiOTI1MmM3NTQ4MTc3NDYxNmZjZWJlNzUwNWM3ZGZhZDNmYTNmYWIzMTEyOGFlNzc2ZWQyNzY3NzVhZDMzIn19fQ=="}

]}}}

which is a custom head generated on the website minecraft-heads.com on a video tutorial a guy just posted the code in his command block pressed a button and voila it was in his inventory. I do it and I get nothing.

I have spent 2 days reading articles, watching videos and there is no reason why this isn't working for me. I have tried, changing my difficulty level. I have tried levers and buttons, I have tried altering the code. I cannot get this to work. PLEASE HELP. there is another website where you can get the code of a custom banner too and those also don't work. I can't even get my command block to give me a basic player head with a /give mrs_esa88 player_head command... my command blocks don't give me anything and I am totally mind boggled.

I have read there is a way to enable command blocks on a server but since I didn't create a server I don't have server.properties folder to edit and make the enabling command blocks "true"

I read on minecraft.net (for the featured block of the week which just happens to be command blocks) that you are currently changing the way they work entirely.. is this true?? what element am I missing? please help.

I don't have my transaction Id. I hope that is ok. My husband bought this for me back in 2010? 2011? and he used the email papodaca@gmail.com to purchase it for me.

if you can help me I would be so happy! I feel like I am missing out on a very important creative chunk of minecraft.