Mark Zuckerberg Scolds FB Employees For 'Black Lives Matter' Feud

0226-mark-kuckerberg-tmz-01Mark Zuckerberg's Facebook experience is starting to look like the average FB user's -- 'cause it's getting all racial, and he's pissed about it. 

Facebook HQ has a "signature wall" where employees can write messages. Some have chosen to write "black lives matter" ... but others have been crossing it out and replacing it with "all lives matter."

Zuckerberg, in an internal FB post obtained by Gizmodo, called the defacing "unacceptable," adding he was "disappointed by this disrespectful behavior."

He went on to say they are investigating the incidents.