[OS X TeX] citeauthor changes {\ss} to ss?

[Stephan Hochhaus]

Hello list,

I have an entry in my bibtex file that has this for the author:
Ernst Ulrich Gro{\ss}e

In the bibliography at the end of my document this looks fine and  
actually outputs: Große, Ernst Ulrich, but in the text when I use  
\cite{grosse:74} it always prints:
Grosse (1974) in small caps (which looks nice, but I need the ß).

Is this an issue with small caps or rather with jurabib/LateX?
I am using the latest jurabib 0.6 version and gwTeX under Mac OS X  
10.3.3.

Any help is appreciated,

Stephan

This is what's in the preamble:
\documentclass[11pt]{scrartcl}
\usepackage{ngerman}
\usepackage[paper=a4paper,left=60mm,right=20mm,top=25mm,bottom=25mm]{geo 
metry}
\usepackage{graphicx, multicol, jurabib, pstricks, covington}
\jurabibsetup{
          authorformat=smallcaps,
          ibidem=strict,
          titleformat=colonsep,
          see,
}
\renewcommand*{\bibbtsep}{In: }
\renewcommand*{\bibjtsep}{In: }
\usepackage[T1]{fontenc}
\usepackage{lmodern}

And the .bib file entry:
@book{grosse:74,
	Address = {Stuttgart, Berlin, K\"{o}ln, Mainz},
	Annote = {7 Textklassen werden eingeteilt},
	Author = {Gro{\ss}e, Ernst Ulrich},
	Publisher = {Kohlhammer},
	Title = {Texttypen. Linguistk gegenw\"{a}rtiger Kommunikationsakte.  
Theorie und Deskription},
	Year = {1974}}

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