why I can't break

Hi all,
I've a target packet with arma.
I can't understand the following behavior:
if i set a breakpoint to writeprocessmemory from the start
and i hit f9 it doesn't stop and the program starts as
without the debugger.
if i set the breakpoint after some code stepping
(for example after stopping on a CreateProcess)
i can break in writeprocessmemory.
why does it happen?

thanks,
and cheers.

I believe this is the memory protection in newer versions of Armadillo. If you try and set a breakpoint Arma will detect the cc at the beginning of the api and crash. However if you set a breakpoint further down inside the api (like WriteProcessMemory) Arma will not detect it and it will break. Do you know what version of Arma your program is packed with?

mmmm..
the problem as i've described is a little different.
I'm not saying i can break on the writeprocessmemory only on
the final piece of code, but that i can break on writeprocessmemory
(at the start of the function) only after some code of the arma is executed

CommandBar:
He WriteProcessMemory.