Hello, I tried another debugger (J-Link) and it worked, then I tried connecting with ST-Link V2 again and it worked too.Thanks to everyone who tried to help.

I'm sorry its my mistake, i should to give a lot more detail.What debugger (software & hardware) were you using? I'm using IAR Embedded Workbench IDE 9.40 and ST-LINK V2What is your target hardware? My target hardware is NXP MKM34Z256VLL7. I tried ST...