Problems with umlaut in index entry

[Robert Neumann]

Hello,
I have a Problem with a german umlaut in index entries: The entry is test� the 
error is displayed as:

LaTeX Error: Command \textcurrency unavailable in encoding T1.
   \item test\~A\IeC {\textcurrency }
                                       , 5

I am using Lyx 1.3.4 on SuSE Linux 9.1
Thanks
Robert