Titlesec

Come mai attraverso il codice seguente, che usa titlesec, i titoli delle sottosezioni non vengono stampati? Grazie per ogni eventuale risposta.

`
\documentclass[svgnames,10pt,italian,a4paper,twoside,leqno,pdftex]{book}

\usepackage{color}

\usepackage[pdftex]{graphicx}
\DeclareGraphicsExtensions{.pdf,.png,.jpg,.mps}
\RequirePackage[colorlinks,hyperindex,plainpages=false,pdfpagelabels]{hyperref}
\hypersetup{
pdftitle={Eserciziario},
pdfsubject={Appunti del corso},
pdfauthor={nome},
pdfcreator={\LaTeXe},
pdfkeywords={algebra, analisi matematica},
pdfpagemode=Useoutlines,
colorlinks,
urlcolor=white
}

\usepackage{tikz}
%\usepackage{kpfonts}
\usepackage[explicit]{titlesec}
\newcommand*\chapterlabel{}
\titleformat{\chapter}
{\gdef\chapterlabel{}
\normalfont\sffamily\Huge\bfseries\scshape}
{\gdef\chapterlabel{\thechapter.\ }}{0pt}
{\begin{tikzpicture}[remember picture,overlay]
\node[yshift=-3cm] at (current page.north west)
{\begin{tikzpicture}[remember picture, overlay]
\shade[top color=MidnightBlue,bottom color=LightSkyBlue] (0,0) rectangle
(\paperwidth,3cm);
\node[anchor=east,xshift=.9\paperwidth,rectangle,
rounded corners=20pt,inner sep=11pt,
fill=MidnightBlue]
{\color{white}\chapterlabel#1\color{Black}};
\end{tikzpicture}
};
\end{tikzpicture}
}
\titlespacing*{\chapter}{0pt}{50pt}{-60pt}

\titleformat{\subsection}[frame]
{\normalfont}
{\footnotesize\bfseries
\enspace\thesubsection\enspace \filleft}
{2pt}
{\rule{0.0mm}{3.6mm}
\bfseries\filright
\color{MidnightBlue}
\hspace{.25em}}

\usepackage[a4paper,text={17.5cm,24cm},centering]{geometry}
\usepackage{fancyhdr}

\usepackage[latin1]{inputenc} %accenti
\usepackage{babel} %sillabazione
\usepackage{amsfonts} %font ams
\usepackage{amssymb}
\usepackage{amsmath} %matematica
\usepackage{amsthm} %teoremi
\usepackage{multicol}
%\usepackage{enumerate}
\usepackage{ifthen}
\usepackage{cancel}
\usepackage{eurosym}
\usepackage{textcomp}
%\usepackage{multirow}
\usepackage{tabularx}
\usepackage{calc}

\usepackage{draftwatermark}
\SetWatermarkAngle{60}
\SetWatermarkLightness{0.96}
\SetWatermarkFontSize{0.5cm}
\SetWatermarkScale{6}
\SetWatermarkText{provai}

\usepackage{enumitem}
%\usepackage{moduli/mathpack} %creato da me e personale
%\usepackage{moduli/esercizi} %creato da me per gli esercizi

\theoremstyle{plain}
\newtheorem{teo}{Teorema}[section]
\newtheorem{cor}[teo]{Corollario}
\newtheorem{lem}[teo]{Lemma}
\theoremstyle{definition}
\newtheorem{pro}[teo]{Proposizione}
\newtheorem{dfn}[teo]{Definizione}
\newtheorem{dfnpro}[teo]{Definizione-Proposizione}
\newtheorem{oss}[teo]{Osservazione}
\newtheorem{esr}[teo]{Esercizi}
\newtheorem{tof}[teo]{Questionario}
\newtheorem{ese}[teo]{Esempio}
\newtheorem{rem}[teo]{Nota}
\newtheorem{prb}[teo]{Problema}
\newtheorem{alg}[teo]{Algoritmo}

\columnsep=1.2cm
\columnseprule=0.1pt %se diverso da zero visualizza una linea che separa le colonne
\renewcommand{\columnseprulecolor}{\color{Gray}}

\pagestyle{fancy}
\renewcommand{\chaptermark}[1]{\markboth{\thechapter.\ #1}{}}
\renewcommand{\sectionmark}[1]{\markright{\thesection.\ #1}}
\fancyhf{}

\fancyhead[LO,RO]{
\begin{tikzpicture}[remember picture,overlay]
\node[yshift=-1.8cm] at (current page.north west)
{\begin{tikzpicture}[remember picture, overlay]
\shade[top color=MidnightBlue,bottom color=LightSkyBlue] (0,0) rectangle (\paperwidth,3cm);
\node[anchor=west,yshift=0.9cm,xshift=.075\paperwidth]{\color{white}\normalfont\sffamily\bfseries\scshape\rightmark};
\node[anchor=east,yshift=0.9cm,xshift=.925\paperwidth]{\color{white}\normalfont\sffamily\bfseries\scshape\thepage};
\end{tikzpicture}
};
\end{tikzpicture}
}

\fancyhead[LE,RE]{
\begin{tikzpicture}[remember picture,overlay]
\node[yshift=-1.8cm] at (current page.north west)
{\begin{tikzpicture}[remember picture, overlay]
\shade[top color=MidnightBlue,bottom color=LightSkyBlue] (0,0) rectangle (\paperwidth,3cm);
\node[anchor=west,yshift=0.9cm,xshift=.075\paperwidth]{\color{white}\normalfont\sffamily\bfseries\scshape\thepage};
\node[anchor=east,yshift=0.9cm,xshift=.925\paperwidth]{\color{white}\normalfont\sffamily\bfseries\scshape\leftmark};
\end{tikzpicture}
};
\end{tikzpicture}
}

\fancyfoot[RO]{
\begin{tikzpicture}[remember picture,overlay]
\node[yshift=-1.0cm] at (current page.south west)
{\begin{tikzpicture}[remember picture, overlay]
\shade[top color=white,bottom color=MidnightBlue] (0,0) rectangle (\paperwidth,3cm);
\node[anchor=west,yshift=1.8cm,xshift=.075\paperwidth]{\href{mailto:nome@gmail.com}{nome@gmail.com}};
\node[anchor=east,yshift=1.8cm,xshift=.925\paperwidth]{\href{http://www.sito.com/it}{http://www.sito.com/it}};
\end{tikzpicture}
};
\end{tikzpicture}
}

\fancyfoot[RE]{
\begin{tikzpicture}[remember picture,overlay]
\node[yshift=-1.0cm] at (current page.south west)
{\begin{tikzpicture}[remember picture, overlay]
\shade[top color=white,bottom color=MidnightBlue] (0,0) rectangle (\paperwidth,3cm);
\node[anchor=east,yshift=1.8cm,xshift=.925\paperwidth]{\href{mailto:nome@gmail.com}{nome@gmail.com}};
\node[anchor=west,yshift=1.8cm,xshift=.075\paperwidth]{\href{http://www.sito.com/it}{http://www.sito.com/it}};
\end{tikzpicture}
};
\end{tikzpicture}
}
\renewcommand{\footrulewidth}{0pt}
\renewcommand{\headrulewidth}{0pt}
\fancypagestyle{plain}{
\fancyhead{}
}
\definecolor{evidenziatore}{RGB}{241,255,207}

\makeatletter
\def\cleardoublepage{\clearpage\if@twoside \ifodd\c@page\else \hbox{} \vspace*{\fill}
\begin{center}
%commenti
\end{center}
\vspace{\fill} \thispagestyle{empty} \newpage \if@twocolumn\hbox{}\newpage\fi\fi\fi}
\makeatother

\begin{document}
\frontmatter
%\input{frontespizio.tex}
%\input{ringraziamenti.tex}
\tableofcontents
\mainmatter
\newgeometry{textheight=24cm,inner=1.8cm, outer=4.5cm, headsep=3cm, headheight=3cm}
\chapter{Integrali}
\section{Integrali indefiniti}
\subsection{Integrali risolvibili mediante decomposizione in somma}
\input{analisi_matematica/in_una_variabile/integrali/tecniche_di_integrazione/metodo_della_decomposizione_in_somma.tex}
\section{Integrali impropri}
\subsection{Criteri di convergenza}
\input{analisi_matematica/in_una_variabile/integrali/integrali_impropri/criteri_di_convergenza.tex}
\end{document}`