There is a known issue where accepting Energy gifts does not register on Facebook. Please start by accepting just a few Energy gifts at a time and refreshing the game afterwards. After the game is refreshed the Energy should appear on your account.
Please note that there is a max limit of 75 daily Gifts limit and the Energy bar maxes out at 75. If your Energy is at 75 already, we recommend playing before accepting more gifts.
If you continue to experience issues accepting Energy gifts, please contact our Support Team by going to support.rockyou.com