NRF51822AA s110 DFU problem update (from softdevice ver.7 to ver.8 with dualbnank)

[LQ_creator]

I generated two packages for OTA. The first package contains a bootloader and a softdevice 7.3.0. The second one contains a bootloader and a softdevice 8.0.0. I flash the device with NRFgo Studio.
After that, I want to do a DFU upgrade from version 7 to version 8 but it doesn't work.
From version 7 to 7 it works fine and from version 8 to 7. Can someone help me with this?

[LQ_creator]

problem-solving (flag Enable sofdevice protection must be disabled)