# Missing a vertical line in multicolumn table

I have a table as shown below which is missing a horizontal line across a \multicolumn as shown below

The code I used is

\begin{figure}[!h]
\flushleft
\begin{minipage}[c]{0.6\textwidth}
\centering
\includegraphics[width=1\linewidth,valign=c]{images/chap4/comparingThoughputQos0}
\end{minipage}
\centering
\begin{minipage}[c]{0.38\textwidth}
\centering
\renewcommand{\arraystretch}{1.0}
\begin{tabular}{| c | c | c |}
\hline
\multirow{2}{*}{$\lambda_{{RE}}$}   & $NS_{{1}}$ & $NS_{{2}}$                \\
\cline{2-3}
& \multicolumn{2}{c}{$\mu_{RE-SCEPA}$}   \\
\hline
50   & 00   & 00   \\
200  & 00   & 00   \\
500  & 00   & 00   \\
1000 & 00   & 00   \\
2000 & 00   & 00   \\
3000 & 00   & 00   \\
\hline
\end{tabular}
\end{minipage}
\caption{Impact of number of sensors on $\mu_{RE}$ for different $\lambda_{{RE}}$}\label{fig:comparingThoughput}
\end{figure}


What am I doing wrong?

\multicolumn{2}{c|}{$\mu_{RE-SCEPA}$}

\multicolumn overwrites a previous definition