[Newbie Problems] AttributeError from CGI script?

[steve_w at localhost.localdomain]

I'm trying to use Python in a CGI script for the first time and 
have run into a problem I don't understand.  I get the subject
error message when trying to do a string.replace using one of
the values returned by the form that trigers the script.

The line of code looks like:

line = string.replace(line,"placeholder",form["target"].value)

I get an error message back saying:

Traceback (innermost last):
File "[my script's file name]"
   line = string.replace(line,"placeholder",form["target"].value)
AttributeError: replace

Could someone help me figure out what this error message means?

Thanks in advance,

Steve Wall
steve_w at visi.com