Due to a recent update in Facebook’s privacy, all of your FarmVille 2 activities can only be seen by friends who have installed the game.
The "Invite Friends to be your Farmhands!" page will only show Facebook friends playing FarmVille 2.
There are other areas in the game where you will be able to invite your friends.
On the “Send gifts to Selected friends”, "Invite Friends to Join your Co-Op!" and "Invite Neighbors to Join you in FarmVille 2", you will find a "Invite Friends" tab that will open a Facebook dialog where you will be able to invite your friends.
On the "Get Some Help from your Friends" section the tab "Fill all Helper Slots" will open the Facebook dialog as well.
There is also a new tab called “Double the Items!” under “Ask for more resources”, that works the same way as the old “Ask for ingredients” tab, where you can ask your friends to share some resources with you.
If you wish to play with your other Facebook friends in the game, simply click on the “Invite Friends” tab to take you to this Facebook dialog box. This dialog box will allow you to invite Facebook friends to install FarmVille 2.