"! Misplaced \omit" error

Question

The code below describes a table that goes like:

|_|x x|x x|

|x|x|x|x|x|

|x|x|x|x|x|

where

|_| = empty cell, |x x| = multicolumn{2}, |x| = cell with text in it.

\begin{tabular}{c|c|c|c|c|}
\label{tlc}
\cline{2-5}
& \multicolumn{2}{|c}{1 Sec Trials} & \multicolumn{2}{|c|}{100 Sec Trials} \\
\hline
\multicolumn{1}{|c|}{Target Rate} & Mean & Std. Dev & Mean & Std. Dev \\
\hline
\multicolumn{1}{|r|}{1Hz} & 1.07 & 1.08 & 1.22 & 0.11 \\
\multicolumn{1}{|r|}{5Hz} & 4.71 & 2.09 & 4.51 & 0.21 \\
\multicolumn{1}{|r|}{10Hz} & 10.3 & 3.28  & 10.1 & 0.32 \\
\multicolumn{1}{|r|}{100Hz} & 93.6 & 9.91 & 94.6 & 0.97 \\
\hline
\end{tabular}

However, when I run it I get an error that reads

! Misplaced \omit.
\@cline #1-#2\@nil ->\omit
\@multicnt #1\advance \@multispan \m@ne \ifnum \@...
l.60 \cline{2-5}
I expect to see \omit only after tab marks or the \cr of
an alignment. Proceed, and I'll ignore this case.

I've Googled around and it seems that people often get errors like this when nesting \multicolumns inside \multirows, or when they put text in the cell before starting the \multicolumn. But that is not the case in my code.

Can anyone tell me what is going on??

Answer 1

You cannot place a \label as the first element in a cell. If you're interested in labelling the table, place the tabular in a table environment, add a \caption and place the \label after it:

\documentclass{article}
\begin{document}
\begin{table}
  \centering
  \begin{tabular}{c|c|c|c|c|}
    \cline{2-5}
    & \multicolumn{2}{|c}{1 Sec Trials} & \multicolumn{2}{|c|}{100 Sec Trials} \\
    \hline
    \multicolumn{1}{|c|}{Target Rate} & Mean & Std. Dev & Mean & Std. Dev \\
    \hline
    \multicolumn{1}{|r|}{1Hz} & 1.07 & 1.08 & 1.22 & 0.11 \\
    \multicolumn{1}{|r|}{5Hz} & 4.71 & 2.09 & 4.51 & 0.21 \\
    \multicolumn{1}{|r|}{10Hz} & 10.3 & 3.28  & 10.1 & 0.32 \\
    \multicolumn{1}{|r|}{100Hz} & 93.6 & 9.91 & 94.6 & 0.97 \\
    \hline
  \end{tabular}
  \caption{Here is a caption}\label{tlc}
\end{table}
\end{document}

Here is a booktabs alternative to your tabular:

\documentclass{article}
\usepackage{booktabs}% http://ctan.org/pkg/booktabs
\begin{document}
\begin{table}
  \centering
  \begin{tabular}{r*{4}{c}}
    \toprule
    & \multicolumn{2}{c}{1 Sec Trials} & \multicolumn{2}{c}{100 Sec Trials} \\
    \cmidrule(lr){2-3} \cmidrule(lr){4-5}
    Target Rate & Mean & Std. Dev & Mean & Std. Dev \\
    \midrule
    1Hz & 1.07 & 1.08 & 1.22 & 0.11 \\
    5Hz & 4.71 & 2.09 & 4.51 & 0.21 \\
    10Hz & 10.3 & 3.28  & 10.1 & 0.32 \\
    100Hz & 93.6 & 9.91 & 94.6 & 0.97 \\
    \bottomrule
  \end{tabular}
  \caption{Here is a caption}\label{tlc}
\end{table}
\end{document}

Answer 2

I stumbled in this problem too, and I solved it as I tried to create the MWE, so I am reporting for future references, maybe it's trivial, but sometimes you can miss it when you have big tables. I wanted to have the first row cells bold and centered, so I tried:

    \documentclass{article}
    \begin{document}
    \newcommand{\myh}[1]{\textbf{\multicolumn{1}{c}{#1}}}

    \begin{tabular}{|ccccc|}
    \myh{99} & \myh{4} & \myh{3} & \myh{2} & \myh{1}\\
    \end{tabular}
    \end{document}

The solution was:

    \newcommand{\myh}[1]{\multicolumn{1}{c}{\textbf{#1}}

That is: formatting inside multicolumn and not outside. Hope it helps.

Answer 3

I was using the longtable environment and got the \omit error message, too. In my case I had the caption/label integrated also in front of the table content. By integrating a \\ after the label command, the error message is avoided.

Answer 4

Ensure you haven't redefined span! I had

\def\span#1{\ensuremath{\text{span}\left(#1\right)}}

in my preamble. Took me ages to figure it out.