AMQ4.1.1: Use of asyncDispatch

[uma_rk]

I am using ActiveMQ 4.1.1 with a very simple peer to peer 
connection. I find that after a few exchanges, the messages
from A to B stall - the clients of A seem to hang while sending 
a message (FWIW, only TextMessages are used):

  Peer A:
       <transportConnectors>
       <transportConnector  name="openwire" 
              uri="tcp://localhost:61616?wireFormat.maxInactivityDuration=0"/>
    </transportConnectors>

    <networkConnectors>
        <networkConnector name="remote-broker" uri="static://(tcp://B:61616)" />
    </networkConnectors>

Peer B:
       <transportConnectors>
       <transportConnector  name="openwire" 
              uri="tcp://localhost:61616?wireFormat.maxInactivityDuration=0"/>
    </transportConnectors>

    <networkConnectors>
        <networkConnector name="remote-broker" uri="static://(tcp://A:61616)" />
    </networkConnectors>

I would ike to understand what could be causing this problem.
At the smetime I want to enable asyncDispatch.

When the URL syntax

     tcp://localhost:61616?asyncSend=true 

is rejected as "bad connetion parameter". The same result with

    tcp://localhost:61616?broker.asyncSend=true


Please help!

Regards

/Ur