#+OPTIONS: latex:t

Hello,

I just made a clean installation of org packages and contrib in order to
be able to convert latex equations in gnus. But I meet the following
problem that I am going to describe: 

Generating a png image seems to work via M-x org-preview-latex-fragment

\begin{equation}
((A \to B) \to A) \to A
\end{equation}

But with M-x org-mime-htmlize, the png image is not loaded. Why? Your
help is welcome. 

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