you are not providing DC with any file/configuration that describes the technology, so it cannot understand how the wires behave and how to estimate the wirelength.
Thanks for your reply. As the "lib" file shows, I think this library already defines the technology. Should I also need to define it in my script?
Shows in the "lib" file
wire_load("5K_hvratio_1_1") {
capacitance : 1.774000e-01;
resistance : 3.571429e-03;
slope : 5.000000;
fanout_length( 1, 1.7460 );
fanout_length( 2, 3.9394 );
fanout_length( 3, 6.4626 );
fanout_length( 4, 9.2201 );
fanout_length( 5, 11.9123 );
fanout_length( 6, 14.8358 );
fanout_length( 7, 18.6155 );
fanout_length( 8, 22.6727 );
fanout_length( 9, 25.4842 );
fanout_length( 11, 27.0320 );
}
default_wire_load : "5K_hvratio_1_1" ;