Unable to set software breakpoints in IAR IDE

I'm using IAR Embedded Workbench to debug a Cortex-M0 system interfaced through ST-LINK/V2 SWD. The processor isn't officially supported because it is under development, but the configuration files have been updated with correct data. I'm not sure however if the environment has all the needed info. I am able to set up to 6 breakpoints (2 of which should be traces) but I can't set software breakpoint at all. Could you help me?