Feynman diagrams with feynarts

Question

I'm trying to draw Feynman diagrams with the feynarts.sty package for LaTex. The problem is that if I write the following code:

\begin{feynartspicture}(150,150)(1,1)
   \FADiagram{}
   \FAProp(0.,10.)(6.,10.)(0.,){/Straight}{0}
   \FALabel(3.,9.18)[t]{$1$}
   \FAProp(20.,10.)(14.,10.)(0.,){/Straight}{0}
   \FALabel(17.,10.82)[b]{$2$}
   \FAProp(6.,10.)(14.,10.)(0.8,){/Straight}{0}
   \FALabel(10.,5.98)[t]{$3$}
   \FAProp(6.,10.)(14.,10.)(-0.8,){/Straight}{0}
   \FALabel(10.,14.02)[b]{$4$}
   \FAVert(6.,10.){0}
   \FAVert(14.,10.){0}
\end{feynartspicture}

I get this:

Instead of this:

In practice I get only the label of the propagators but not the propagators. How can I solve this problem?

Answer 1

I solved my own problem. I just need to add

% !TEX TS-program = latex

in the first line of the LaTeX file.