Sometimes friend codes don't give a reward. It is the feature of the game. 
There is a certain amount of luck involved. 
Sometimes you get up to 2 Piastres.

To keep out of any bad effect on the game, please change time zones and avoid change the time manually. Also it is better to be done when your game is closed.

Buildings can be placed only on cleared areas next to the road. A place that is available for construction is highlighted with green colour. The entrance of the building should be adjacent to the road. Please, mind the surface! There are buildings that require sand, water and land as a foundation.

The problem occurred when you changed Apple ID on your device. You should contact Apple Support concerning this matter to resolve the issue.
To do that, please follow the link: http://www.apple.com/support/

A player can invite 10 friends and accept 20 invitations a day.

Nano Generator is a special time-limited offer.
The game feature is that you can buy up to five Nano Generators.

You can add friends using "Sociality" (an icon with three people in the right lower corner) -> "Friends" -> "Invite a friend."

You can find "Sociality" button in the right lower corner of the screen (an icon with three people depicted on it).

You can redeem it within the game itself.
Open "Sociality" -> "Services" -> "The gift code" and enter the given code.
(You can find “Sociality” it in the lower right corner of the screen. There is a button with three people depicted on it.)

You can find Gift codes in the game blog, our Facebook community, or on our partners' websites.
Please, keep following the news in our blog and Facebook page. Codes are given for participating in events and other activities.

Each level-up or your achievement is followed  by a pop-up window with a checkmark "Post to Facebook", "Send to Twitter".
Deselect this checkmark  and news won't be posted.

If you change your system's clock time or date it affects on game. In that case changing system date and/or time is cheating and it is not allowed to do while playing game. If you did so, you could get unfair advantage and you were permanently blocked for using some features.