Comments form malfunction

Hi folks. I’m using Twenty Twelve, child theme. URL: http://www.perthpunk.com

The author of one of the pages on the site tells me she is unable to get her comments to go through. Readers of the page have commented without problem, and I just tried it myself – no problem.

It seems weird that the Comments are not working for one person only (she’s in email contact with me, and I have emailed her a snapshot of the comments form and reply button to make sure she knows what to do). I don’t know how to troubleshoot this. Does anyone have any ideas, please?

The URL of the page I’m referring is here.

Cheers
Ross