I am Niketas Constantinidis from Thessaloniki, Greece. It has only been three weeks since I have first been introduced to LaTeX. Trying to figure out a feature, but then I bump into another one and another one...

I have a question that most of you guys will find rather easy.

-----------
\begin{table}[htb]
\caption{Conventional relations}
\begin{center}
\begin{tabular}{llll}
\toprule
Correlation
&\multicolumn{2}{l}{Conditions}
& Range of validity \\
\cline{2-3}
& Geometry & Flow regime \\
\hline
$equation goes here$
& & \\
$equation goes here$
\end{tabular}
\end{center}
\end{table}
---------------------
which works fine but I also need to number the mathematical formulae. So I wrap them inside \begin{equation}...\end{equation}, but then I get "LaTeX error: Bad math environment delimiter". I included the \usepackage{amsmath} preamble. The editor is Winefish LaTeX editor on Ubuntu Linux.
After many searches over the Internet and in this forum, I couldn't find anything related to my problem. Since I didn't want to open a new topic for this simple question, I wanted to append it to a warm hello note.
Any help would be appreciated.
Thanks in advance,
Niketas