To add asynch. reset at Stratus example-1

Hi I'm newbie in HLS

For stratus example-1, I have one question.

I expected that I could add async. reset for all f/f/ but I couldn't add at the output data registers while all other f/fs were synthesized with async. reset.

What I changed was

SC_CTOR( dut )

{

    SC_CTREAD( thread_function, clk.pos() );

    reset_singal_is( rst, 0 );  --> async_reset_signal_is( rst, 0 );

    din.clk_rst( clk, rst ); --> din.clk_rst_async( clk, rst );

    dout.clk_rst( clk, rst ); --> dout.clk_rst_async( clk, rst, false);

 }

All synthesized f/fs except output data f/f have async. reset.

f/f with async. reset : always_ff( posedge clk or negedge rst)

output data f/f : always_ff(posedge clk)

So what I missed ?