/blockdata command help

I wrote this command to make a chest constantly replace the items inside itself, the problem is that the command worked for the first part (command block) but if I try to add a second item like the button the command stops working.

How can I solve this problem?

Command:

/blockdata 3 56 0 {Items:[{id:137,Count:1,Slot:12,tag:{HideFlags:1,Unbreakable:1,display:{Name:"Command Block",Lore:["Write Commands Here!"]},ench:[{id:4,lvl:2}]}}],[{id:143,Count:1,Slot:13,tag:{HideFlags:1,Unbreakable:1,display:{Name:"Button",Lore:["Activate Commands!"]},ench:[{id:4,lvl:2}]}}]}