Hello everybody,


I do not succeed to get correct results with exporting .png images for html files with specific formulas , for example, 

with 



#+OPTIONS: tex:dvipng


the formula 

\begin{prooftree}
\AxiomC{\scriptsize{1}}
\noLine
\UnaryInfC{[\neg A \land A]}
\RightLabel{\scriptsize{\land E}}
\UnaryInfC{\neg A}
\AxiomC{\scriptsize{1}}
\noLine
\UnaryInfC{[\neg A \land A]}
\RightLabel{\scriptsize{\land E}}
\UnaryInfC{A}
\RightLabel{\scriptsize{\neg E}}
\BinaryInfC{\bot}
\RightLabel{\scriptsize{\to I~1}}
\UnaryInfC{(\neg A \land A) \to B}
\end{prooftree}

does not give a correct .png image for browsers. 

Suggestions? 
(with imagemagick it is not better). 

Thanks

Jo.