compress?

Hi all ,
I am going to compress data transmit between sever and client .
I had set "-z" on each endpoints.

But I don't know why it dosen't take any effect.
Data size number in network trace is same as before.

Is my setting wrong?

here is my config

#
# The client reads this property to create the reference to the
# "hello" object in the server.
#

Ice.Default.Locator=IcePack/Locator:default -h victorchan -p 10000 -z

Hello.Proxy=hello:tcp -p 10000 -h victorchan -z

#
# The server creates one single object adapter with the name
# "helloadapater". The following line sets the endpoints for this
# adapter
#
Hello.Endpoints=tcp -p 10000 -h victorchan -z:udp -p 10000 -h victorchan -z
#
# Warn about connection exceptions
#
Ice.Warn.Connections=1

#
# Network Tracing
#
# 0 = no network tracing
# 1 = trace connection establishment and closure
# 2 = like 1, but more detailed
# 3 = like 2, but also trace data transfer
#
Ice.Trace.Network=3

#
# Protocol Tracing
#
# 0 = no protocol tracing
# 1 = trace protocol messages
#
Ice.Trace.Protocol=0

Ice.MessageSizeMax=1024000

#
# Security Tracing
#
# 0 = no security tracing
# 1 = trace warning messages
# 2 = config file parsing warnings
#
#Ice.Trace.Security=2

#
# Glacier settings
#
Glacier.Router.Endpoints=default -p 10005 -h victorchan -z
Glacier.Router.Client.Endpoints=tcp -z:udp -h victorchan -z
Glacier.Router.Trace.Client=2
Glacier.Router.Trace.RoutingTable=1

#
# Uncomment the following lines if you want to run this demo with Glacier
#
#Ice.Default.Router=Glacier/router:default -p 10005

Can any one tell me what i need to do in order to compress all data in transmission?