Koma-script with etoolbox package

Koma-script with etoolbox package

I try use boolean expresion which it has been shown on my MNWE:
\documentclass[12pt, b4paper, twoside]{scrbook}
\usepackage[log-declarations=false]{xparse}
\usepackage{xltxtra}
\usepackage{etoolbox}
\usepackage{amsmath, amsthm, amssymb, amsfonts, amsbsy}
\newbool{pboldvectors}%
\booltrue{pboldvectors}%
\ifbool{pboldvectors}%
{\renewcommand{\vecc}[1]{\mathbf{#1}}} % then clausule
{\renewcommand{\vecc}[1]{\vec{#1}}} % else clausule
\begin{document}
\begin{equation}
\vecc{x}
\end{equation}
\end{document}
but without success. I have got Latex error: \vecc is undefinned. Before,
I used the library ifthen, but it has been obsolete. I would like to use
this switch for mathematical formatting.