# Error with integral

I got an error when I evaluated third equation in the beginners tutorials. I got following message. I just evaluated notebook which is downloaded from tutorial page.

> Undefined control sequence:
>
> }\intF
> Note that all symbols which you use in cadabra have to be valid LaTeX
> expressions. 

As it said the next line in tex file caused problem.

> \$\setstretch{2.5}{} - \frac{1}{4}\intF^{\mu \nu} F_{\mu \nu}\,\,{\rm d}x\$

After following a few more steps, I found this is a only problem of showing the result in $\LaTeX$ form. So it may not be a critical bug, but how can I fix it?

You must add an space between the \int command and the F letter