Resident ratio shows negative number

Create 10 instant in ec2 and install membase server 1.7.2r-15
Create a cluster of 10 nodes
Load 250K items with 200K per item to cluster.
Check resident ratio, it shows negative number.

Crashing process
initial_call

{mochiweb_socket_server,acceptor_loop,['Argument__1']}

pid <5898.888.0>
registered_name []
error_info
{exit,

{error,closed}

,
[

{mochiweb_socket_server,acceptor_loop,1}

,

{proc_lib,init_p_do_apply,3}

]}
ancestors
[menelaus_web,menelaus_sup,ns_server_sup,ns_server_cluster_sup,
<5898.52.0>]
messages []
links []
dictionary []
trap_exit false
status running
heap_size 233
stack_size 24
reductions 105