why can't I set up a breakpoint in eclipse?

For some odd reason, I can't use breakpoints in my eclipse project. All breakpoints that I set have a diagonal line on them, above the dot in the respective line (on the left margin of the window), as if they are blocked. When I run in debug mode, the breakpoints are ignored. Any ideas?

You've probably just pressed "Skip All Breakpoints" in the Breakpoint view - simply press it again.

Default key bindings are: Ctrl + Alt + B.

This doesn't exactly answer the OPs question, but when trying to double click to add break points, I was getting messages stating "this feature is not enabled".

I had to right click on the break point bar and select "Breakpoint Types" -> "C/C++ Breakpoints" instead of "Default". Then it worked fine.

in python, I had to go to: windows->perspective->Open Perspective->Debug then select the Breakpoints tab and make sure the zero with the slash (skip all breakpoints) is not selected (you can also use Ctrl-Alt-B to toggle it).

1. Open Debug View
2. Open Breakpoint Perspective
3. Right-click all breakpoints there
4. Press Enable