Getting SERVERERROR when I tried communicating with Memcached C Library using memcached_add()

I am trying to establish connection from Memcached C Client to Couchbase server. I see connection object created successfully ( Memcached object created Successfully:: 0x1176010 ), but I am getting the SERVER ERROR when I tried memcached_add() with 10 bytes of data.
May I know what could be the issue here.
Also I tried memslap which is part of couchbase as below, but even this is also throwing error.
./memslap -s -S 5s
servers :
threads count: 1
concurrency: 16
run time: 600s
windows size: 10k
set proportion: set_prop=0.10
get proportion: get_prop=0.90
memslap: clients/memslap.c:793: ms_print_memslap_stats: Assertion `pos <= buf’ failed.

Appricate your help/inputs in this regard.


What the version of libmemcached are you using?

I am using