strange bibtex error

I was writing a scientific paper with latex and left it aside for a while, when I came back to it some days ago, I was unable to get bibtex working, though I did not change the file. I get an error message as follows for every entry of the database:

You're missing an entry type---line 83684 of file bibliography.bib
 : @
 :   manual{dionextn20,
I'm skipping whatever remains of this entry
You're missing an entry type---line 83694 of file bibliography.bib
 : @
 :   manual{dionextn21,
I'm skipping whatever remains of this entry

and the entries in the .bib file look like this:

@manual{dionextn20,
  title = {Dionex Technical Note 20 - Analysis of Carbo开发者_开发问答hydrates by High Performance
    Anion Exchange Chromatography with Pulsed Amperometric Detection
    (HPAE-PAD)},
  organization = {Dionex Corporation},
  address = {Dionex Corporation 1228 Titan Way P.O. Box 3603 Sunnyvale, CA, USA},
  year = {2000},
  key = {LPN 032857-04 5M 6/00}
}

@manual{dionextn21,
  title = {Dionex Technical Note 21 - Optimal Settings for Pulsed Amperometric
    Detection of Carbohydrates Using the Dionex ED40 Electrochemical
    Detector},
  organization = {Dionex Corporation},
  address = {Dionex Corporation 1228 Titan Way P.O. Box 3603 Sunnyvale, CA, USA},
  year = {1998},
  key = {LPN 034889-03 3.5M 10/98}
}

When looking at the bibtex command output, it looks like the @ and the entry type are in a different line. But in the file they are not. I've tried to replace :%s/@manual/@manual/g in vim, but it did not help. Can anyone help me? thanks.

It seems that your BibTeX style file (*.bst) doesn't have the @manual entry type. Perhaps your style file has changed.