Malcolm:
There a number of things which you did incorrectly:
(1) CZ does not accept svg images. If you look at Commons page for the svg image that you referred us to (
http://commons.wikimedia.org/wiki/File:Golden_Rectangle_Construction.svg), just below the main image at page top, there are links to four png versions: 200px, 500px, 1000px and 2000px sizes. Click on one of those, copy it to your computer and then upload it to CZ.
(2) It is not enough to simply state "Commons" as the source. You should include the actual url of the Commons page for the png version you select in (1) above.
(3) The CZ upload template (or Wizard) asks for the country of first publication (or to state that you don't know) ... which you did not provide.
(4) The CZ upload template asks you to provide a credit line and it gives you a link to instructions on how to do that ... which you also did not provide.
I know that seems like a lot of "make work" but there are good reasons for for providing the items asked for.
I see that Daniel re-uploaded the 99px png version for you. If you want me to upload one of the larger versions for you, please tell me which size you want and I will be happy to do it.
Milt Beychok