algorithm2e 和 \numberwithin 与部分

Question

我正在使用该包algorithm2e，具体来说，\usepackage[ruled,vlined,linesnumbered,noresetcount]{algorithm2e}创建了以下算法：

    \documentclass[12pt]{article}
%
\usepackage{amsmath}
\usepackage{blindtext}
\usepackage{caption}
%\usepackage{algorithm,algorithmic}

\usepackage[ruled,vlined,linesnumbered,noresetcount]{algorithm2e} 
\numberwithin{algorithm}{section}
%
\begin{document}

%
\section{Example of GA}
\label{sec_1}
\blindtext

\begin{algorithm}[h!]
 \KwData{The fitness function $f$, a stop criterion.}
 \KwResult{An approximation of $f^{*}$ and the point where is attained. }
\textbf{Initialization}\;  
 \begin{enumerate}[(a)]  
 \item $\mathrm{ExitLoop}\leftarrow \mathrm{false}$.
 \item Generate an initial population $P$.
 \item Evaluate the fitness at each point of $P$.
 \item Best point selection on $P$, $p^{*}\leftarrow \arg \min\{f(p):p\in P\}$, and its value $f(p^{*})$. 
 \end{enumerate}
\nl \textbf{Loop}\; 
   \While{$\mathrm{ExitCondition}= \mathrm{false}$}{
\nl\textbf{Update the population}\;
\begin{enumerate}[(a')]  
 \item Using selection, crossover and mutation prefixed rules, generate \newline a new population $P'$
 \item $P\leftarrow P'$.
 \item Compute  $p^{*}$ and $f(p^{*})$ as in (d). 
 \end{enumerate}
\nl \textbf{Decision}\;
  \If{stop criterion is attained}{
   $\mathrm{ExitLoop}\longleftarrow \mathrm{true}$\;
   \Return{$p^{*}$ and $f(p^{*})$}\;
   } 
 }
 \caption{General scheme of a GA}
 \label{alg_1_10}
\end{algorithm}
 %
\end{document}

算法生成正确，但标题显示“算法 1：GA 的一般方案“， 代替 ”算法 1.1：GA 的一般方案“，这就是我想要的。

该命令\numberwithin{algorithm}{section}生成以下错误：

! LaTeX Error: No counter 'algorithm' defined.See the LaTeX manual or LaTeX Companion for explanation.Type H <return> for immediate help.... \numberwithin{algorithm}{section}

出了什么问题？