Error in Packet sending - How to track???

[gopalpatil]

I am facing a problem to receive some .exes from server to client.
Let me explain details:
We have a program that sends some exes to client machine via TCP. But sometimes those exes received to the client partially. e.g. if the actual size of the exe is 1423 KB then it would receive very less than 1423KB.
Both machines (client and server) are in different networks. when i try to debug TCPs in DebugView tool, observed some errors as below:
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ABCUtils - Downloading file 'ABCTest.exe'.
ABCAVS - Enter ServiceClose
ABCAVS - Exit ServiceClose
TABCClient::SendPacket - ERROR: Error reading file data.
Error Sending Packet - 11
ABCUtils - Attempting to locate proxy information.
ABCUtils - Could not locate proxy information.
ABCUtils - Looking for an ABCRelay on the network.
Error Sending Packet - 11
ABCUtils - ERROR: Unkown error sending message.
ABCBeacon - Send Time Out
--------------------------------------------------------
I guess it may be a problem in Sending packets from the server. b'coz sometimes it goes successful and sometimes not. I am not sure since i m not n/w specialist. :-)
Please let me know where may be problem or how can i track the probelm and find out loophole. How to track Packet communication to find out exact problem.

Thanks in advance,
GP.