Blockchain websocket is missing a transaction

So I have implemented a Blockchain websocket to my NodeJS, but it misses a transaction if I'm monitoring a address. What is the problem?

Function to start monitor:

function monitorAddress(address){
    logger.trace("Starting to monitor address: " + address);
    ws.send('{"op":"addr_sub", "addr":"' + address + '"}', function (error){
        if(!error){
            logger.info('Monitoring has been started for address: ' + address);
        }
    });
}

Pinging every 25 Seconds

setInterval(function () {
    ws.send('{"op":"ping"}', function (error) {
        if (!error) {
            logger.info("Successfully pinged after 25 seconds.");
        }
    });
}, 25 * 1000);

Answer from Blockchain

ws.on('message', function incoming(data, flags){
    var obj = JSON.parse(data);
    console.log(data);
    if(obj.op == 'utx'){
       //transaction
    }
)};

via Jordn