Can not flash MCU samd21

[lorenz]

Hello,
I'm use Olimex ARM-USB-OCD-H with SWD-Interface to programming a SAMD21j18-Chip. I'm use OpenOCD too.
If i use normal Command (openocd -f /d/Project/l_me/BTExtender/work/BTE/debug/debug.cfg -c "program interface/BTE.axf verify reset exit") then programming failt with Command:

Error: Failed to read memory at 0x000044c0
Error: Can't read NVM status
Error: samd_write: write failed at address 0x00004480
Error: error writing to flash at address 0x00000000 at offset 0x00000000

Sometimes programming was completed successful, but mostly it was failt with this Error.

If i use the Command with Debug-Informations (openocd -f /d/Project/l_me/BTExtender/work/BTE/debug/debug.cfg -c "program interface/BTE.axf verify reset exit" -d), then programming was always completed successful and failt never.

If i used an other Debugger programming was always completed successful, too.

Can anyone help me please? I think it is a timing-probleme, but can not change clock of SWD in OpenOCD...