nnir problems

[sorry . already . too . much . spam]

Hello.

nnir always prints an error, although I use a very simple setup. Do
you know what's wrong?

Thanks,
  Sebastian


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setup in .emacs:
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(require 'nnir)
(setq nnir-mail-backend (nth 0 gnus-secondary-select-methods)
      nnir-search-engine 'swish-e)


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error when trying "G G Test"
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Opening nnir server on -ephemeral...done
Doing swish-e query ((query . Test))...
swish-e args: -f /home/sfischme/Mail/index.swish-e -w Test
Massaging swish-e output...done
Doing swish-e query ((query . Test))...
swish-e args: -f /home/sfischme/Mail/index.swish-e -w Test
Massaging swish-e output...done
Doing swish-e query ((query . Test))...
swish-e args: -f /home/sfischme/Mail/index.swish-e -w Test
Massaging swish-e output...done
Doing swish-e query ((query . Test))...
swish-e args: -f /home/sfischme/Mail/index.swish-e -w Test
Massaging swish-e output...done
Doing swish-e query ((query . Test))...
swish-e args: -f /home/sfischme/Mail/index.swish-e -w Test
Massaging swish-e output...done
Retrieving newsgroup: nnir:((query . "Test"))...
Fetching headers for nnir:((query . "Test"))...
if: nnheader-parse-head returned nil for article 509 in group 
nndoc+gnus-help:mail.other