[Tuglist] put an environment in between one row of tabular

[Baskaran]

Dear sirs,

I need to put an environment in between one row of  tabular for the
following example. 
But it says Error "missing brace". If it is a single column covered by an
environment,
there is no problem. Could you please say a good solution

\documentclass{article}
\newenvironment{xxxx}{}{}
\begin{document}
 \begin{tabular}{llll}
\begin{xxxx}
sssssss
& 1.2   &1x2    &1,2  \end{xxxx} \\
1.2   & 1.2   &1x2    &1,2    \\
 1.23  & 1.23  &12x5   &300,2  \\
 1121.2& 1121.2&861x20 &674,29 \\
 184   & 184   &10     &69     \\
 .4    & .4    &       &,4     \\
       &       &x4     &\\
 \end{tabular}
\end{document}

Thanking you

N.K.Baskaran