Could it be that you don't have focus on the Icon field? Click your cursor in there and see if it works.
I am also testing this application (my compliments to the chef's), so if you want, feel free to contact me via IM:
Yahoo: jamie_jenkins
AOL: jjenkinsaaa
I'm a Notes admin, and not an expert on domBulletin, but I may have already encountered some of your pitfalls and would be happy to help if I can.