# Problem with appendix numbering [closed]

I have looked all questions about appendix but I could not solve my problem. I am writing my thesis, composed of three chapters. In one chapter, I have an appendix. The problem is that I could not numbering it correctly. For example, I get this for chapter 3 in the Contents:

...

3 The chapter three

3.1 Subsection of chapter 3

...

3.6 Conclusion

.1 Appendix

.1.1 The solution

But I want:

...

3.6 Conclusion

3.A Appendix

3.A.1 The solution

I am using this line in the main.tex file:

\usepackage[titletoc,title,header]{appendix}


Inside the chapter 3 tex file I have this:

\begin{appendices}
\section{Appendix}
\subsection{The solution}

Blah Blah...

\end{appendices}