Problems with biblatex-dw and idembib/idembibformat

[jezZiFeR]

Hello,

I have the following problem with biblatex-dw and idembib/ 
idembibformat: Although I have entered idembib=true and  
idembibformat=dash, I do not get dashes, but "ders.", which is the  
male entry in german. How could I solve this? Thanks for your help.

LyX 1.6.9. In the document-settings I have entered the following:
\usepackage[natbib=true,style=footnote- 
dw 
,urldate 
=long,abbreviate=true,pageref=true,idembib=true,idembibformat=dash] 
{biblatex}