r - knitr's kframe producing errors in LaTex, no shadecolor for code chunks -

i using r's knitr , latex create pdf. technic center gives "!undefined control sequence" build output errors. technic center indicates lines \begin{kframe} , \end{kframe} problematic lines.

removing kframe environment resolves errors build output, document not display shadecolor code chunks when kframe environment removed.

i updated miktex packages , knitr. document's preamble includes \usepackage{framed}; \usepackage{xcolor} not seem influence problem. changing knitr background option did not fix problem.

here preamble of document in rnw file (knitr adds this):

\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 question} \author{author changed 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} 

thank you!