[Q] Can't flash with fastboot topic

Hi everyone,

i rooted my z1c, backuped TA, unlocked bootloader and recovered TA. The firmware is .157 since it arrived me.

But everytime i try to flash a kernel or recovery in fastboot i gives mit this error message.
(flashing kernel for example)

Code:

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./fastboot flash boot ../../LS-KK-MileStone-3.2-amami/boot.img
sending 'boot' (11352 KB)...
OKAY [  0.358s]
writing 'boot'...
FAILED (remote: Command not allowed)
finished. total time: 0.361s

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I am on archlinux with newest android sdk.
Is there something wrong with recoverying the TA partion after unlock? Or needs fastboot more parameters?
I banged my head for this since hours... Got someone a idea.