When i compile the following code, i get the package keyval error, undefined code. Please help!
\documentclass{beamer}
\usepackage[frenchb]{babel}
\usepackage[T1]{fontenc}
\usepackage[latin1]{inputenc}
\usepackage{newcent}
\usepackage{color}
\usetheme{Warsaw}
\setbeamercolor{normal text}{teal}
\begin{document}
\begin{frame}
\setbeamertemplate{background canvas}[vertical shading][top=white,bottom=blue]
Texte n'ayant pas encore subi de changement de couleur.
\end{frame}
\end{document}