Please suggest what went wrong in my code

Question

My code are follow:

\documentclass{book}
\usepackage[normalem]{ulem} 
%\newcommand{\cmark}{\ding{51}}%
\newcommand{\xmark}{\ding{55}}
%\usepackage{kpfonts}
%\usepackage{mdwlist}
%\usepackage{fixltx2e}
\usepackage{pifont}
\usepackage{tree-dvips}
\usepackage{tikz,tikz-qtree,tikz-dependency}
\usepackage{gb4e}
\noautomath
\usepackage{linguex}
\usepackage{showframe}
\def\ShowFrameLinethickness{0.125pt}
\begin{document}
We examine this issue through the lens of a language family that has received considerable attention in research on syntactic ergativity: the Mayan family. Mayan languages have been a particularly compelling testing ground for theories of syntactic egrativity because, while all of them exhibit ergative-absolutive marking, only some exhibit syntactic ergativity. For example, Q'anjob'al does not allow the ergative subject to be directly extracted \ref{initialqan}, while Ch'ol does \ref{initialchol} (see Coon, Mateo Pedro, and Preminger (CMP) 2014). %\nocite{CoonMateoPreminger:2014}
%%%%%%%%%%%%%%%%%%%%test%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\begin{exe}
\ex
\gll Wenn jemand in die W"uste zieht ... \
If  someone in the desert draws and lives ... \
\trans `if one retreats to the desert and ... '
\end{exe}
%%%%%%%%%%%%%%%%%%%%test%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\end{document}

I got error, please can any one suggest what went wrong in my tag?....