Issue with Linguex package in chapters

Question

I'm having some issues with Linguex package when I want to use \ex. in other chapters in my document. It shows me this error:

./EncabezadoTesisMSc.tex:100: Runaway argument? \a . John es inglés pero es temperamental \b . inglés(john) $\wedge \ETC. File ended while scanning use of \ex. <inserted text> \par l.100 \include{Kap3/Kap3}

So I look over ./EncabezadoTesisMsc.tex:100 and look arround for any troubles in the code. But there's no issue because I already used the linguex package in the prevoius chapter: kap2/kap2

I'm going to copy and paste the relevant code from the preamble.

    \documentclass[12pt,spanish,fleqn,openany,letterpaper,pagesize]{scrbook}

\usepackage[utf8]{inputenc}
\usepackage[spanish]{babel}

\usepackage[]{linguex}


\usepackage{Befehle}


\begin{document}
\pagenumbering{roman}
\include{HojaTitulo/HojaTituloMSc}


    {\newpage{\pagestyle{empty}\cleardoublepage}}
\pagenumbering{arabic}
\include{Kap1/Kap1}
\include{Kap2/Kap2}
\include{Kap3/Kap3}
\include{Kap4/Kap4}
\include{Kap5/Kap5}

\end{document}

In Kap3.tex file I just try to use and then appears the error.

\chapter{this is chapter 3}
\ex. some example

Answer 1

You need an empty line to terminate the argument of \ex.

This works:

\documentclass{article}
\usepackage[]{linguex}
\begin{document}
\ex. some example

\end{document}

This does not, but gives the error File ended while scanning use of \ex.:

\documentclass{article}
\usepackage[]{linguex}
\begin{document}
\ex. some example
\end{document}

Here is a longer example; note the empty lines.

\documentclass{scrbook}
\usepackage[]{linguex}
\begin{document}
\ex. First item
\a. First sub-item of first item
\b. Second sub-item of first item
\a. First sub-sub-item of second sub-item of first item
\b. Second sub-sub-item of second sub-item of first item

\ex. Second item
\a. First sub-item of second item
\b. Second sub-item of second item
\a. First sub-sub-item of second sub-item of second item
\b. Second sub-sub-item of second sub-item of second item

\end{document}