[Plugin: WP to Twitter] Custom tweets only working for adminstrators

I’ve recently been encountering an issue with non-administrator users: they are able to compose custom tweets – i.e. the custom tweet field appears – but these aren’t actually being submitted, and the regular uncustomised tweet is being sent out instead.

I’ve tried various combinations for the user group settings on the WP to Twitter options page, but without success: all I succeed in doing is completely removing some users’ permission to compose tweets.

http://wordpress.org/extend/plugins/wp-to-twitter/