Legenda não aparece no gráfico de barras

Question

Eu tenho um gráfico de barras onde parte do conjunto de dados não contém pontos para todas as coordenadas x.

Eu tenho dois problemas:

1. Os rótulos das legendas não aparecem
2. O símbolo na legenda é uma barra dupla. Por que é que? Não deveria ser uma única barra?

Além disso, como tenho muito espaço vazio dentro do gráfico (canto noroeste), posso colocar a legenda lá?

Obrigado

\documentclass[preprint,1p,times]{elsarticle}

\usepackage{pgfplots}

\pgfplotsset{height=6cm, compat=1.9}

\begin{document}

\newcommand \SingleName {Single}
\newcommand \DoubleName {Double}
\newcommand \ScalarName {Scalar}
\newcommand \SSEName {SSE}
\newcommand \AVXName {AVX} 

\newcommand \MorinOffsetName {Khuong Offset}
\newcommand \MorinBranchyName {Khuong Branchy}
\newcommand \LowerBoundName{lower\_bound}
\newcommand \BitSetNoPadName{Lead Bit No Pad}
\newcommand \ClassicModName{Classic Mod}

\newcommand \ClassicName {Classic}
\newcommand \ClassicColor {magenta}
\newcommand \ClassicMark {*}
\newcommand \ClassicStyle {solid}

\newcommand \ClassicOffsetName {Offset}
\newcommand \ClassicOffsetColor {green}
\newcommand \ClassicOffsetMark {*}
\newcommand \ClassicOffsetStyle {solid}

\newcommand \BitSetName {Lead Bit}
\newcommand \BitSetColor {green}
\newcommand \BitSetMark {*}
\newcommand \BitSetStyle {solid}

\newcommand \EytzingerName {Eytzinger}
\newcommand \EytzingerColor {blue}
\newcommand \EytzingerMark {*}
\newcommand \EytzingerStyle {solid}

\pgfplotsset{every axis/.append style={
    font=\small,
        line width=0.6pt,
        }}


\begin{figure}[ht]
\begin{tikzpicture}
\begin{axis}[
    width  = 0.85\textwidth,
    height = 5cm,
    major x tick style = transparent,
    ybar=2.5*\pgflinewidth,
    bar width=2.5pt,
    ymajorgrids = true,
    ylabel = {Throughput},
    ytick={0, 50, 100, 150, 200, 250, 300, 350, 400, 450, 500, 550, 600},
    symbolic x coords={\ClassicName,\LowerBoundName,\MorinBranchyName,\MorinOffsetName, \ClassicModName,\ClassicOffsetName,\BitSetName,\EytzingerName},
    xtick = data,
    xticklabel style={rotate=45, anchor=east},
    scaled y ticks = false,
    enlarge x limits=0.08,
    ymin=0,
    legend pos=outer north east,
]

  \addplot[style={red,fill=red,mark=none}]
coordinates {(\EytzingerName,170.465) (\BitSetName,199.79) (\ClassicOffsetName,184.861) (\MorinOffsetName,146.236) (\MorinBranchyName,64.4379) (\ClassicName,53.0333) (\LowerBoundName,62.4723) (\ClassicModName,152.575) };
\addplot[style={orange,fill=orange,mark=none}]
coordinates {(\EytzingerName,171.929) (\BitSetName,199.421) (\ClassicOffsetName,187.638) (\MorinOffsetName,147.191) (\MorinBranchyName,63.5857) (\ClassicName,50.8408) (\LowerBoundName,63.7888) (\ClassicModName,153.149) };
\addplot[style={blue,fill=blue,mark=none}]
coordinates {(\EytzingerName,381.08) (\BitSetName,383.956) (\ClassicOffsetName,379.795) (\ClassicModName,244.268) };
\addplot[style={cyan,fill=cyan,mark=none}]
coordinates {(\EytzingerName,260.645) (\BitSetName,263.8) (\ClassicOffsetName,254.917) (\ClassicModName,151.602) };
\addplot[style={green,fill=green,mark=none}]
coordinates {(\EytzingerName,385.152) (\BitSetName,386.348) (\ClassicOffsetName,381.327) (\ClassicModName,253.413) };

\addplot[style={yellow,fill=yellow,mark=none}]
    coordinates {(\EytzingerName,264.892) (\BitSetName,216.624) (\ClassicOffsetName,214.466) (\ClassicModName,138.059) };

 \legend={\SingleName-\ScalarName,\DoubleName-\ScalarName,\SingleName-\SSEName,\DoubleName-\SSEName,\SingleName-\AVXName,\DoubleName-\AVXName}
 %   \legend={a,b,c,d,e,f}
\end{axis}

\end{tikzpicture}
\vspace*{-5mm}
\caption{Throughput in millions of searches per second with array X of size $N=15$ and array $Z$ of size $M=2048$ randomly generated}
\label{fig:selectbinary}
\end{figure}

\end{document}