Everytime someone comments on a black lives matter post with an all lives matter response. This is what you are literally doing.
Your unconscious privilege allows you to silence a cause and dismiss the importance of a message that you have deemed incorrect.
Your unconcious privilege allows you to gag our struggle and dilute our message. You are literally trying to control what we say and how we express our angers and frustration towards the systemic racism that we experience everyday. So next time you feel the need to say all lives matter, maybe you will stop and think.