javascript - Redis wrong type error -

i doing system in node redis. problem when try save new "array" in redis rpush or lpush drops type error:

[error: wrongtype operation against key holding wrong kind of value] 

here code use:

redis_client.rpush(board_name, data.concentration, function(err, reply){     if(err){         console.log('error: ', err);     }     else{         console.log(board_name + 'has saved new concentration value redis.');     } }); 

i've made tests , when value of board_name "ssas" (random board name name) fails example if "hola" works.