treasure chest in opprison when mining pls help

[srapgamerYT]

when i mining i found treasure chest and when i want to open it it just give me a message say "hey! sorry but you cannot open that here"
some say it ''maybe because someone else found that treasure chest'' but im mining alone and someone else say ''it has 1/10 chance of getting the treasure chest loot''
but i got the treasure chest more than 20 time and still get the message