getAndLock not locking

bucket.getAndLock(item.id,

{ lockTime: 10 }

, function (error, package) {
if (error) {
if (error.code === 11)

{ return fn('locked'); }

else

{ return fn(error); }

} else

{ return fn(null, package.value, package.cas); }

});

I have this code running 3-4 times in parallel. It always goes through on 2 processes ... that's not locking.