I cannot change the color of the page number at right bottom. The setting applied to black but still be white, why?
How can I change the one to black??
¥documentclass[dvipdfmx,11pt,notheorems]{beamer}
¥usetheme{Madrid}
¥usefonttheme{professionalfonts}
¥setbeamertemplate{frametitle}[default][left]
¥setbeamertemplate{navigation symbols}{}
¥setbeamercovered{transparent}
% Footer
¥setbeamertemplate{footline}[page number]
¥setbeamerfont{footline}{size=¥normalsize, series=¥bfseries}
¥setbeamercolor{footline}{fg = black, bg = black}
¥usepackage{amsmath,amssymb}
¥usepackage{amsthm}
¥usepackage[T1]{fontenc}%
¥usepackage{textcomp}%
¥usepackage[utf8]{inputenc}%
¥usepackage{otf}%
¥usepackage{helvet}%
¥begin{document}
¥begin{frame}¥frametitle{test}
¥begin{block}{aaa}
¥begin{itemize}
¥item aaa
¥item bbb
¥end{itemize}
¥end{block}
¥begin{exampleblock}{Example}
¥begin{equation*}
¥frac{¥pi}{2} =¥left( ¥int_{0}^{¥infty} ¥frac{¥sin x}{¥sqrt{x}} dx ¥right)^2 =¥sum_{k=0}^{¥infty} ¥frac{(2k)!}{2^{2k}(k!)^2} ¥frac{1}{2k+1}
=¥prod_{k=1}^{¥infty} ¥frac{4k^2}{4k^2 - 1}
¥end{equation*}
¥end{exampleblock}
¥begin{exampleblock}{Example}
¥begin{equation*}
¥frac{¥pi}{2} =¥left( ¥int_{0}^{¥infty} ¥frac{¥sin x}{¥sqrt{x}} dx
¥right)^2 =¥sum_{k=0}^{¥infty} ¥frac{(2k)!}{2^{2k}(k!)^2} ¥frac{1}{2k+1}
=¥prod_{k=1}^{¥infty} ¥frac{4k^2}{4k^2 - 1}
¥end{equation*}
¥end{exampleblock}
¥begin{exampleblock}{Example}
¥begin{equation*}
¥frac{¥pi}{2} =¥left( ¥int_{0}^{¥infty} ¥frac{¥sin x}{¥sqrt{x}} dx ¥right)^2 =¥sum_{k=0}^{¥infty} ¥frac{(2k)!}{2^{2k}(k!)^2} ¥frac{1}{2k+1}
=¥prod_{k=1}^{¥infty} ¥frac{4k^2}{4k^2 - 1}
¥end{equation*}
¥end{exampleblock}
¥end{frame}
¥end{document}