Help on uvm_pw_scoreboard package.

I am using uvm_pw_scoreboard package available on accelera Contributions.I have following queries about it .

1. Why does this package uses uvm_analysis_export and analysis_fifo implementation instead of uvm_analysis_imp in pw_checker_predictor as well as pw_scoreboard.

2. I want to pass unique id to each transaction, to do this i have implemented as below:

my_local_predictor.sv file(not extended from pw_checker_predictor)

uvm_analysis_port #(item) predict_port;

predict_port = new ("predict_port",this);

item.set_transaction_item(unique_id);

$display("Predictor unique_id =%d",unique_id);

predict_port.write(item)

In extended pw_scoreboard

function int get_stream_id(uvm_transaction t )

     $display("Scoreboard unique_id =%d",t.get_transaction());

     get_stream_id = t.get_transaction_id();

endfunction

Output:

Predictor unique_id = 2;

Scoreboard unique_id= -1;

Any help is appreciated.