Ok - I took a closer look at the network-chat example and seems it doesn't compile for Symbian out of the box.
First, in chatdialog.cpp there's
But there's no sendButton defined in the chatdialog.ui - you'll have to add it there, or come up with some other way to trigger the message sending (with contents of lineEdit).
connect(sendButton, SIGNAL(clicked()), this, SLOT(returnPressed()));
This error comes from /examples/network/qftp/sym_iap_util.h, which the network-chat also includes. There's a following line in sym_iap_util.h:
Illegal use of incomplete struct/union/class 'QTextCodec'
-> remove the comment and see if it helps