c# - New line in textbox -

i have textbox1 lets user input text, button adds text textbox2. code doesnt create new line when add text.

 string date = datetime.now.tostring();  txt_details.text = date + "  " + txt_summary.text.tostring() +    environment.newline + environment.newline ; 

notice += operator.

txt_details.text += "\n" + date + "  " + txt_summary.text.tostring();