Can't encrypt e-mail

[Tim Schumacher <tim@bandenkrieg.hacked.jp>]

Hi Folks,

when I try to send an encrypted e-mail to a group of certain people I
get the following messages:

Do you want to encrypt? (y or n)  y
This message will be encrypted.
Saving file +draft/6...
Saving...
Undo!
user-error: No undo information in this buffer

Also sometimes I get the message 'Translation error'.

I suspect some of the keys of the people are in some way or another
faulty but I can't see anything wrong with them.

My wanderlust version and associated components can be seen in the
header.

thanks a lot

Tim