When I saw this problem come in, I was reminded of problems I have of elog crashing.  So I tried attaching a .bmp file to an entry.  In my case it did not crash, but it did not run ImageMagick either - it just gave a link as it it were a zip or tar file - that is to say no .png image had been generated and shown.   As I've never attached a .bmp file before, I don't know whether elog allows for them to be processed and a thumbnail made, a quick look in the documentation didn't enlighten me, but then I didn't look for that long either.  (I'm running 2.9.2 svn 2475, under Slackware 13 which is a version post some image processing issues I reported to Stefan - might that explain why in my case?). 

I have found that sometimes elog will crash, but effectively after it has done the action - so if it crashes when asked to move files from one logbook to another, you find the entries have been moved.  In my case, I believe the crashes are due to memory issues, nothing I can state for certain.

It would possibly help Stefan and Andreas if you can tell whether the .bmp file appears in the relivent logbook directory (usually a subdirectory of ....../logbooks) - it will have been renamed as yymmdd_hhmmss_{filename}.bmp - except, of course, the date and time will be showing not these symbols - and if the entry with which you have tried to attach this .bmp file been written - using a text viewer on the file yymmdda.log (obviously the day will be today, i.e. the one just updated as you tried the entry.   I have come across orphan attachment files in directories in my time, possibly from when elog crashed part way through an action.

(If I am stating the obvious, apologies, I don't know your level of experience with elog or linux, so trying to cover all possible levels)