[Tex/LaTex] Equation-reference with cleveref

cross-referencingequationsntheoremtheorems

I am using cleveref, which seems to be working fine, except for my equation references, which are referenced as ??.

My equation is:

\begin{equation}\label{ex2eqn}
Y_{t} = \epsilon_t + 1.8Y_{t-1} + 0.8Y_{t-2} + 0.2Y_{t-6} - 0.36Y_{t-7} + 0.16Y_{t-8}
\end{equation}

and my reference is

This transformation is done by inserting $Y_{t-1}$ into \Cref{ex2eqn}, then $Y_{t-2}$ and so on.

A minimal working example is:

\documentclass[11pt]{article}
\usepackage{amsmath}
\usepackage[thmmarks]{ntheorem}
\usepackage{cleveref}
\begin{document}
\begin{equation}\label{ex2eqn}
e=mc^2
\end{equation}
A reference: \Cref{ex2eqn}.
\end{document}

Best Answer

Load ntheorem with the amsmath (compatibility) package option.

\documentclass[11pt]{article}
\usepackage{amsmath}
\usepackage[amsmath,thmmarks]{ntheorem}
\usepackage{cleveref}
\begin{document}
\begin{equation}\label{ex2eqn}
e=mc^2
\end{equation}
A reference: \Cref{ex2eqn}.
\end{document}
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