Problem with Adhesive

On my fanfiction archive, I installed Adhesive 1.5 and posted some sticky posts without problems – but when I went back to edit some of them today, the ‘sticky’ tick box had disappeared. I deactivated the plugin, reinstalled it, also tried 1.6a, but with no success – the tick box has gone. There is a custom field ‘sticky’, but setting the value to 1 doesn’t have any effect.
Could another plugin be interfering? Active are Ria’s Drop-down categories with the ability to exclude, Scott’s Get Custom Field Values and Kitten’s Show Category Posts.
Any help would be appreciated, because I’m currently changing the date by hand to keep the post at the top of the page…