URL links not working from included PDF title page

I included a separate PDF page as my main front page for a large LaTeX document. That PDF page was made with LaTeX using the hyperref package, and contains several linked URL elements (source of front page image, email linked to author’s name,…). As seen separately in my PDF browser, that PDF title page is working perfectly.

But then, after compilation of the whole document, the title page don’t have URL links anymore. Why? How can I fix this? The whole document is working great, except that front page wich doesn’t have its links anymore.

Here’s a MWE code to play with:

documentclass[11pt,letterpaper,twoside]{book}
usepackage[T1]{fontenc}
usepackage{lmodern}
usepackage[total={6in,10in},left=1.5in,top=0.5in,includehead,includefoot]{geometry}
usepackage{amsmath}
usepackage{amsfonts}
usepackage{mathtools}
usepackage{tensor}
usepackage{pdfpages}
usepackage[unicode,colorlinks,linkcolor=blue,urlcolor=red,citecolor=blue,pdftitle={Title},pdfauthor={Name},pdfsubject={Subject},pdfkeywords={some words},pdfproducer={pdfLaTeX},plainpages=false,hyperindex=true,pdfpagelabels,linktocpage=true]{hyperref}

begin{document}

includepdf{TitlePage.pdf} % Not included in this example.  This page contains some URL links.

TEST

end{document}