Memcached not returning the stored bytearray

Question

Amazon Elasticache used as Memcached to store a Inputstream (converted to byte array) like so

private static final int MEMCACHED_TIME_TO_LIVE = 15 * 60;
InputStream stream = item.openStream();

byte[] byteArray = IOUtils.toByteArray(stream);


MemcachedClient memcachedClient = new MemcachedClient(new InetSocketAddress(AMAZON_ELASTICACHE_CLUSTER_ENDPOINT,AMAZON_ELASTICACHE_CLUSTER_PORT));
String key = name;

Future<Boolean> result = memcachedClient.set(key, MEMCACHED_TIME_TO_LIVE,byteArray);

memcachedClient.shutdown();

The stored byteArray is read like so

MemcachedClient memcachedClient = new MemcachedClient(new InetSocketAddress(AMAZON_ELASTICACHE_CLUSTER_ENDPOINT,
                    AMAZON_ELASTICACHE_CLUSTER_PORT));

String key = name;
byte[] byteArray = (byte[]) memcachedClient.get(key);
memcachedClient.shutdown();

The byte Array returned is always "null" except for the first time the application starts.

My Question

1. Why Memcached is returning a null byte array except for the first time?
2. How to check if the the byte array is successfully written to the Memcached?