problem of lyx in sidux

[Jan Brosius]

Hello,

I use the sidux OS (=debian sid) and I use the latest debian lyx package 
(1.5.5-1) and lyx version 1.5.5). When I start lyx I get the gui of lyx. When I 
do 
Help --> Tutorial, I get the tutorial in lyx. But when converting this lyx file 
to pdf I get a pop-up error:
"Lyx:Cannot convert file
No information for converting xpm format files to png.
Define a converter in the preferences."

And the lyx app freezes.

How can I remedy this problem?
Jan









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