Putting multiple images in a page

Question

I want to multiple images ( say 7) in page in a tabular form. I'm using the following code,but it produces nothing. Could you please tell me what's the problem with it?

\begin{figure}[ht!]
     \begin{center}
%
        \subfigure[Caption of First Figure]{%
            \label{fig:first}
            \includegraphics[width=0.4\textwidth]{FirstFigure}
        }%
        \subfigure[Caption of Second Figure]{%
           \label{fig:second}
           \includegraphics[width=0.4\textwidth]{SecondFigure}
        }\\ %  ------- End of the first row ----------------------%
        \subfigure[Caption of Third Figure]{%
            \label{fig:third}
            \includegraphics[width=0.4\textwidth]{ThirdFigure}
        }%
        \subfigure[Caption of Fourth Figure]{%
            \label{fig:fourth}
            \includegraphics[width=0.4\textwidth]{FourthFigure}
        }%
%
    \end{center}
    \caption{%
        The l-o-n-g caption for all the subfigures
        (FirstFigure through FourthFigure) goes here.
     }%
   \label{fig:subfigures}
\end{figure}

Answer 1

There are not nothing wrong in your figure float as showed this MWE, but in your document, may be the height of the figures is higher, or the float is too near of the end of the page, or too near to another floats. In these cases LaTeX is unable to find a space appropriate for the options [ht!], so the float is moved to the next page or even more, perhaps to end end of document, until that space is found.

One solution is allow to LaTeX to decide the better place ([htbp]), preferably without violating their rules ([htbp!]) but I suggest only use [tbp] since h aesthetically is not always the best place. Another solution could be move the float two or three paragraphs above (or more). If LaTeX still cannot place all the floats in a elegant way, consider change the design of your manuscript (less floats, more text between floats, more text after floats...). If put the image just "here" is a must, try the option H instead of h! (this option need \usepackage{float} in the preamble)

\documentclass{article}
\usepackage{subfigure}
\usepackage{lipsum}
\usepackage[demo]{graphicx}
\usepackage[utf8]{inputenc}

\begin{document}

\lipsum[1]

\begin{figure}[ht!]
     \begin{center}
%
        \subfigure[Caption of First Figure]{%
            \label{fig:first}
            \includegraphics[width=0.4\textwidth]{FirstFigure}
        }%
        \subfigure[Caption of Second Figure]{%
           \label{fig:second}
           \includegraphics[width=0.4\textwidth]{SecondFigure}
        }\\ %  ------- End of the first row ----------------------%
        \subfigure[Caption of Third Figure]{%
            \label{fig:third}
            \includegraphics[width=0.4\textwidth]{ThirdFigure}
        }%
        \subfigure[Caption of Fourth Figure]{%
            \label{fig:fourth}
            \includegraphics[width=0.4\textwidth]{FourthFigure}
        }%
%
    \end{center}
    \caption{%
        The l-o-n-g caption for all the subfigures
        (FirstFigure through FourthFigure) goes here.
     }%
   \label{fig:subfigures}
\end{figure}

\lipsum[2-5]

\end{document}