adding zoo mates

When I try to add new zoo mates after three I get a warning that I will be blocked if I continue to misuse? What's that all about?

Hey you! Don’t let me catch you adding too many friends or messaging too many users or you’ll wind up getting blocked! You may have seen it yourself, a warning dialog box which pops up and alerts you that your activity is of a rate similar to someone that is abusing the system (a spammer). Every day I receive emails from people that have been banned and they can’t get access to the site and receive no response from Facebook.
How Does Facebook Know You’re a Spammer?
Facebook uses a proprietary algorithm for determining unusual usage. The system automatically disables accounts whereas the reinstatement process is manual. Facebook states that “the speed at which you are acting and the sheer number of actions you have made are both taken into account.” After a little bit of analysis it’s pretty easy to determine what methods are used for determining spam.
Here’s the factors that we’ve determined Facebook uses to block users:
Number of friends - Do you have 20 friends or 1,000 friends? This is important because the more friends you have on Facebook, the more active you probably are on the site. As such, don’t think you’ll be able to blast out messages or wall posts to 300 people when you are friends with 50.
Content Similarity - If you are browsing through the site and writing the exact same wall post on everybody’s wall, there’s a good chance that Facebook considers this spam activity. Get creative and switch up the content you are creating. Otherwise let’s be honest, you are acting like a spammer … right?
Average Message Usage - How active is your Facebook inbox? If you receive 40 messages a day, you shouldn’t be punished for replying to them. [We assume that] Facebook calculates an average message usage for each user. If you fall outside a certain statistical deviation from your normal usage, you will be warned and possibly banned.
Time - A sudden surge in usage will set off Facebook’s alarms. If you haven’t sent a message in days but suddenly send out 50, you will look like a spammer.
Facebook Activity Factor - All of these factors (and others that we don’t know of) are used to generate an overall Facebook activity factor for each user. When your overall activity falls outside the statistical norm for you, you will receive a warning. If your usage doesn’t drop to fall within your normal usage levels within a specific time frame, you will be banned.
How to Avoid Being Blocked by Facebook
So now that you know what will get you blocked by Facebook you should pretty much know how to avoid being blocked. Don’t send too many messages, don’t post too many wall posts, don’t go adding friends at a ridiculous rate. Is this model fair? Well that’s really open to philosophical debate but Facebook has to battle spam and the easiest way to play nicely is to stay under the spam radar.