overriding a registered local variable in a sequence from test

Following is the example

class my_sequence extends uvm_sequence...

string file_name;

`uvm_object_utils_begin(mysequence)

`uvm_field_string(file_name,UVM_DEFAULT)

`uvm_object_utils_end

endclass

class basic_test extends from uvm_test

function build_phase(..)

set_config_string("*", "file_name", abc.txt);

endfunction

endclass..

I am passing file_name(abc.txt) from test with set_config_string, but, it is not taking effect.

I did the same thing in driver. it worked well. does UVM supports, overriding local variables in sequence.

Please let me know...

Thanks,

Satya