inquiry/problem/new user

[a.garcia]

I am completely new to lyx... so sorry if my question is 
too newby. I am trying to write a document in Lyx, I 
inserted a TOC, and have some paragraphs. The TOC displays 
ok, but when I try to create a pdf of the lyx file it 
gives me an error msg. It is:

Undefined control sequence.
 ...oduction and Motivation\tableofcontents{}}
The control sequence at the end of the top line
of your error message was never \def'ed. If you have
misspelled it (e.g., `\hobx'), type `I' and the correct
spelling (e.g., `I\hbox'). Otherwise just continue,
and I'll forget about whatever was undefined.
I do not know what to do... sorry but have no idea. What 
am I doing wrong?