Nomencl Error - Unable to produce 2nd line of nomenclature

documentclass[9pt,conference,a4paper,twocolumn]{IEEEtran}

 usepackage{cite}
 usepackage{amsmath,amssymb,amsfonts}
 usepackage{algorithmic}
 usepackage{graphicx}
 usepackage{textcomp}
 usepackage{xcolor}
 usepackage{float}
 usepackage{lscape}
 usepackage{titlesec}
 usepackage{nomencl}

 makenomenclature


 begin{document}


nomenclature{$k$}{set of hourly intervals}
nomenclature{$a$}{index for power}
printnomenclature

end{document}

Why every time I run, it will only show the first line which is ‘k’, and ‘a’ won’t show up. Another mistake is that, every time I tried to edit the nomenclature, it will just repeat the fist specified nomenclature which is ‘k’.
For example: I change this nomenclature{$k$}{set of hourly intervals} to the one below

nomenclature{$t$}{index for time}

However, the output will still present k – set of hourly intervals