How to add a new operation to return text file?

[Chi Ding <chi@xxxxxxxxx>]

Hi all las users
      I added a new new operation "MatlabTest" which is supposed to 
return a text file,
into las, however when I called this operation through web browser, it 
created
an html file which points to a non-existent gif file.
      I added this line into custom.pl file
add_mime('MatlabTest','text/plain'); 
      but it didn't work either.
      How to create an operation and make the auto-created html file 
pointing to a text file?
Any body can help me?
      Thanks a lot, Ding