Help needed uploading image files ( 0kb issue )

[kevin at stallibrass.com]

I'm writing a small app to allow a collegue to easily update a web page. In
it's simplest form, there is one text box and one image to be changed.
I'm handling the text changes by inserting a javascript include script on
the web page and using this app to modify the text file it points to. The
files are updated by using:
put "document.write('" & fld "newtext" &"');document.write"into URL
"ftp://name:password@ftp.website.com/thefile.js"

This works fine, the problem comes with the images. My app imports any image
file and resizes it to fit the area available on the web page. I can use

export image "image1" to file "image1.gif" as GIF  -- This works fine to
create the required file within the local folder

my problem is getting the image to the URL.. I've tried:

 export image "image1" to URL
"ftp://name:password@ftp.website.com/image1.gif" as GIF -- The file appears
but is 0 kb

--libURLftpUpload URL "image1" to URL
"ftp://name:password@ftp.website.com/image1.gif"  -- The file appears but is
0 kb

I've also tried variations of  libURLftpUploadFile, and 

--libURLftpUploadFile
myVariable,ftp://name:password@ftp.website.com/image1.gif"    -- exporting
the file to a variable first.

even copying the correctly saved local file but with the same result

In each case, the file appears where I need it but it's empty - i.e. 0 kb

The image file I'm creating is correct as I can ftp it up to the site with
no problems (not a solution I can offer to my collegue)

I'm obviously missing something fundamental here that I can't stumble on in
the documentation so any help would be very gratefully recieved

Kevin S