STM32 cant set breakpoint in debug mode

Hello,

i setup a stm32f100RBT project with RowleyCWfA 1.7 , conected via jtag 20pin
when i hit debug the debugger runs, i can pause.
it goes in dissasembler mode (i selected source Mode), i can step into and debug in assembler.
but i cant set breakpoints in source and cant debug in source ?

can someone help me here ?

Best regards
Kai