Redmine

I'm using the latest svn version of redmine.

I want to do a change in one issue, for example, put it from Normal to High, or changing the category and when i submit it sais:

« Activity » can't be blank

The problem is that i did no activity on the bug, I don't even have it, I just want to clean missing thing in the issue report.

To work, I set "design" activity but i don't think it's normal.