title: knitr's kframe producing errors in LaTex, no shadecolor for code chunks
body: <p>I am using R's knitr and LaTeX to create a pdf.  Technic Center gives "!Undefined control sequence" for Build Output errors.  Technic Center indicates that lines with \begin{kframe} and \end{kframe} are the problematic lines.</p>
  
  <p>Removing the kframe environment resolves the errors from the Build Output, but the document does not display a shadecolor for code chunks even when the kframe environment is removed.</p>
  
  <p>I updated my MikTex packages and knitr.  The document's preamble includes \usepackage{framed}; \usepackage{xcolor} does not seem to influence the problem.  Changing the knitr background option did not fix the problem.</p>
  
  <p>Here is the preamble of my document in the Rnw file (knitr adds to this):</p>
  
  <pre><code>\documentclass{article}
  \usepackage{Sweave}
  \usepackage{amsmath}
  \usepackage{hyperref}
  \usepackage[margin = 0.5in]{geometry}
  \usepackage{amsfonts}
  \usepackage{amsthm}
  \usepackage{marvosym}
  \usepackage{paralist}
  \usepackage{framed}
  \usepackage{url}
  \usepackage{xcolor}
  \usepackage{array}
  
  \renewcommand\qedsymbol{\Squarepipe}
  
  \title{title changed for question}
  \author{author changed for question}
  
  \newtheorem{theorem}{Theorem}[section]
  \newtheorem{lemma}[theorem]{Lemma}
  \newtheorem{proposition}[theorem]{Proposition}
  \newtheorem{corollary}[theorem]{Corollary}
  
  \newenvironment{definition}[1][Definition]{\begin{trivlist}
      \item[\hskip \labelsep {\bfseries #1}]}{\end{trivlist}}
  \newenvironment{conjecture}[1][Conjecture]{\begin{trivlist}
  \item[\hskip \labelsep {\bfseries #1}]}{\end{trivlist}}
  \begin{document}
  </code></pre>
  
  <p>Thank you!</p>