Fail to insert to new bucket rather than default

I m playing around with membase with c# and when i want to insert to the bucket I created, I FAIL!!!

var mbcc = new MembaseClientConfiguration();

mbcc.Urls.Add(new Uri("http://192.168.1.104:8091/pools/testing"));

var client = new MembaseClient(mbcc);
for(int i = 0;i< 1000;i++)
client.Cas(StoreMode.Set, i.ToString(), i);

This is going to default bucket, even though, i want to insert to testing bucket. why?

can anyone replicate this behavior?