From time to time I lose breakpoint functionality in Delphi.
I thought this to be a Delphi 2009 issue but now I have also it in Delphi XE.
In Delphi 2009 by
Bit late answer but I stumbled on this problem too.
If I activated the MyPackage.bpl (bold) in the project manager with the debug configuration, then compiled it, I could see the IDE registered the debug information (blue dots on left of editor).
But when I activated my MainProject.exe (the one using MyPackage.bpl), those blue dots would disappear, indicating that the debug information is no longer present. After some head scratching, I realized that I did set up a dependency (right click on MainProject.exe -> Dependencies) on the Release configuration of MyPackage.bpl and not on the Debug configuration.
Each time I compiled MyProject.exe, it would link with the Release configuration, not the debug configuration!
So check your dependency configurations!