在Couchbase中设置err

It returns EOF when I use go-couchbase to set data into couchbse.

cl, err := gocb.Connect("http://administrator:passwd@127.0.0.1:8091")
...
pool, err := cl.GetPool("default")
...
bucket, err := pool.GetBucket("default")
...
err = bucket.Set("aaa",0,"bbb")
if err != nil {
    fmt.Println("Set error ", err.Error())
}
bucket.Close()

And then I check the log file named memcached.log, the err info is " not aware of extended error code (no bucket)".

If there is no bucket named default , GetBucket will return the err "No bucket named default".

I don't know why this happens.