Loosing 30-40% messages with Smack library

Hi All,

I am using Smack library for communication between two of my server machines. One Server is Google App Engine(Will call it GAE) server and another is my local machine.
I send messages from my local machine(using Smack) to GAE and it reaches there(always, 100%) and then server respond it by saying ok i received it and processed it. Then client machine receive this message.
Now the problem is that almost 30-40% messages are not being received my Client machine which is using smack library. I checked the server logs and it always says sent messages without error.I tried to send the same message with Gtalk and i always receieve response in Gtalk Chat window, but with smack library i keep loosing my response messages.

For client i am using gmail id and i have make sure that i am not logged in anywhere in any other kind of client.(basically created a new gmail account)
DO you know what is wrong here.

There is one more problem which i am facing, i am not sure if it is related to smack library or my GAE server. if i send more then one message in 10 seconds, i receive my message back to client. So i have to send each message after 10 seconds. Can you please advise what can be wrong here. Or you know that servers can do that. But its very weird as when you chat you dont wait for 10 seconds to send another message. My server says that they can process 3000messages/min.