samr21-xpro debugging goes wrong

Hello everybody,

I try to debug the samr21-xpro board with openocd debugger and get following message:

Starting Debugging

Open On-Chip Debugger 0.10.0+dev-00001-g0ecee83 (2017-02-03-13:31)

Licensed under GNU GPL v2

For bug reports, read

Reading symbols from /home/fw/riot_env/releas_2017_01/RIOT/examples/hello-world/bin/samr21-xpro/hello-world.elf…done.

Remote debugging using :3333

Remote communication error. Target disconnected.: Datenübergabe unterbrochen (broken pipe).

Do someone know what’s going wrong?

P.S. the debugging one the native board works fine, flashing and running the program on samr21-xpro, too.

Best regards,