[texhax] bibtex: Too many commas in name 1

[Andreas Hadjiprocopis]

Dear Texhax,

The following bibtex entry causes bibtex to tell me that:
"Too many commas in name 1 of "S.R.~Arridge, S.R.~Grindrod, A.D.~Linney,
P.S.~Tofts, D.~Wicks" for entry Arridge89
while executing---line 1090 of file plain.bst"

What am I doing wrong? Can't I have as many names as I like in the author
field?

(VERSION: This is BibTeX, Version 0.99c (Web2C 7.3.1)
This is TeX, Version 3.14159 (Web2C 7.3.1)
and I use plain bibstyle and article documentclass)

bibtex entry that causes problem:

@Article{Arridge89,
  author =      "S.R.~Arridge, S.R.~Grindrod, A.D.~Linney, P.S.~Tofts, D.~Wicks",
  title =       "Use of greyscale voxel databases for improved shading and segmentation",
  journal =     "Medical Informatics",
  volume =      "14",  
  number =      "2",
  pages =       "157--171",
  year =        "1989",
  abstract =    "early lesion segmentation I"
}

thanking you in advance,
a.