Books creat in command block with "click event" don't work!

I wrote a book in a command block incorporating "click event".
It worked in the 14w27a snapshot, but since the 14w28a snapshot 14w29b in the book I get an error message:
" Invalid tag book "

Step by step :

• I take and put a command block.
• I write the command :

/give @a minecraft:written_book 1 0
{pages:["
{text:\"Click here to launch\",clickEvent:

"]}

• I active the command block with redstone block, then the book appears in the inventory.
• But when I open the book in my hands, I see the message in the book "invalid tag book." So I can't validate a command from the book, which worked wellyet in the 14w27a snapshot.