Using FindBugs

I just discovered this tool. Very nice, but poorly documented. I've found that even after fixing a bug, it still reports it as a bug unless I create a new project. I can do a clean and build, then deploy in NetBeans, and redo analysis in Findbugs, but the bug is still incorrectly reported unless I create a new project in FindBugs. There has to be an easier way. What am I doing wrong?