Problem inserting .pdf_tex file from Inkscape

I am trying to insert an image from Inkscape. I saved it as a pdf, checking the PDF + Latex option.
Inside my Latex file, I wrote the following code :

\begin{figure}    \centering    \def\svgwidth{\columnwidth}    \input{topo4serv.pdf_tex}  \end{figure}

but when i try to compile using pdflatex, it gives me the following error message:

ERROR: Undefined control sequence.  --- TeX said ---  <argument> \includegraphics                              [width=\unitlength ]{topo4serv.pdf}l.52 ...raphics[width=\unitlength]{topo4serv.pdf}}                                                   %

In the output pdf file the text of the svg file is there but not the shapes...
If someone has an answer i would be very grateful.