how to set sidebar color width

Question

I encountered another problem. I am trying to set the hight of the header and the width of the sidebar. I am using:

\makeatletter
\setlength{\beamer@headheight}{1,2cm}
\makeatother
\newlength\sidebarwd
\setlength\sidebarwd{1.2cm}
\setbeamersize{sidebar width left=\sidebarwd}
\makeatletter
\setlength\beamer@sidebarwidth{\sidebarwd}
\makeatother

What is puzzling me is that the color of the sidebar does not follow the width that I set, while everything looks fine for the header.

I am working on the Singapore theme and the preamble in my swp is:

\newenvironment{stepenumerate}{\begin{enumerate}[<+->]}{\end{enumerate}}
\newenvironment{stepitemize}{\begin{itemize}[<+->]}{\end{itemize} }
\newenvironment{stepenumeratewithalert}{\begin{enumerate}[<+-| alert@+>]}{\end{enumerate}}
\newenvironment{stepitemizewithalert}{\begin{itemize}[<+-| alert@+>]}{\end{itemize} }
\usetheme{Singapore}
\definecolor{unime}{rgb}{.93,.9,.0}
\usecolortheme[named=unime]{structure}
\setbeamerfont{footnote}{size=\tiny}
\useoutertheme{split}
\setbeamertemplate { items } [ball]
\definecolor{lside}{rgb}{.7,.0,.0}
\definecolor{leftFootlineColor}{rgb}{.54,.17, .89}
\useoutertheme{sidebar}
\setbeamercolor{frametitle}{bg=unime}
\setbeamercolor{section in head/foot}{bg=leftFootlineColor}
\logo {\includegraphics[height=1.2cm,width=1.2cm]{uni}}
\setbeamertemplate{sidebar canvas left} [vertical shading]
[top=lside, bottom=lside]
\DeclareGraphicsExtensions{.pdf,.png,.jpg}
\graphicspath{{c:/}}
\makeatletter
\setlength{\beamer@headheight}{1,2cm}
\makeatother
\newlength\sidebarwd
\setlength\sidebarwd{1.2cm}
\setbeamersize{sidebar width left=\sidebarwd}
\makeatletter
\setlength\beamer@sidebarwidth{\sidebarwd}
\makeatother
\input{tcilatex}

In the following picture you can see that the red is larger than the 1.2cm width I set.

What am I doing wrong?

Thanks a lot,

Dario