problem with breakpoint in VS2008

[Minkai]

I'm using Visual Studio 2008 and sometimes when I place a breakpoint, the breakpoint is not hit even though it should have. It says "The breakpoint will not currently be hit. No executable code is associated with this line. Possible causes include: preprocessor directives or compiler/linker optimizations."
What on earth does that mean? Please help, thanks.

[Bazzy]

Can you show the line where you put the breakpoint?
Are you running the debugger?

[helios]

Don't debug builds with optimizations on.