# Cross reference

I am writing an article and when i put the cross references i have a problem. When i compile the article the cross reference appear like "??", i try a lot of things but i can't fix it, could anyone help me please? Thank you!

\subsection{Raw material: selection and classification}
In the present work was used a set of samples corresponding to wells drilled by ANCAP whose location is shown in figure \ref{Drilled zones}. In these wells ANCAP took samples of oil shales that today are kept in good conditions in a warehouse of the company. The analysis each well, in general, can identify different stratigraphic levels, figure \ref{Drill example}. The stratigraphy of the wells shows two distinctive rich organic levels, separated by a layer of siltstones and limestones, called bituminous litter. The deepest bituminous litter has the higher organic matter content. The composition of the rest of the samples are generally inorganic matter like limestones and siltstones.
\begin{figure}[H]
\centering
\begin{overpic}[width=0.4\textwidth]
{Drillzone}
\end{overpic}
\parbox{0.85\textwidth}{\caption{The framework indicate the zone was ANCAP did the drills. In red is indicated the crystalline basement and in yellow is indicated the sendimentarys basins}}
\label{Drilled zones}
\end{figure}

\begin{figure}[H]
\centering
\begin{overpic}[width=0.4\textwidth]%
{Pozoejemplo}
\end{overpic}
\parbox{0.85\textwidth}{\caption{Stratigraphy of the wells}}
\label{Drill example}
\end{figure}


The problem is that \label is used in
\parbox{0.85\textwidth}{\caption{Stratigraphy of the wells}}

outside the \parbox, where the cross reference setting by \caption is no longer available.
Fix: Just put \label inside the \parbox:
\parbox{...}{\caption{...}\label{...}}