I assume user mercurial and sourceforge username are the same? If not, this may be the case when they do not match. They, as you describe, sound as if they are. Have you tried adding @ sourceforge.net or other permutations? I never used sourceforge, so I have no idea, something like this even makes sense.
Otherwise, I suggest directly contacting sourceforge and examining their faq / help, as this sounds like a problem specific to their mercurial setup. I had a similar problem on bitbucket.org, where I wrote βmatteβ under my local name, while my bitbucket username is different. They will then contact this user in the change log, although they do not have access to the project. All I had to do was change the name specified in the eclipse settings, and now everything is fine.
source share