Niko Schwarz wrote: > why does it say that?
because prettyref.sty is not installed on your computer. > what can i do about it? Install it :-) Grab it here: http://ctan.org/tex-archive/macros/latex/contrib/prettyref or try to get it via your package manager (probably the MikTeX package manager). Jürgen BTW the problem with prettyref, which is used by LyX for formatted cross references, was that it had an unclear license, so many TeX distributions excluded it. Recently, the license issue was sorted out, so the package will most likely be reincluded in the distros.
