Cant flash the new firmware (S-On) topic

im trying to flash the new frimware for lollipop
4.16.1540.8+Firmware my Cidnum:HTC__K18 modelid: 0P6B10000
but im getting error on the CMD

C:\android-sdk-windows\platform-tools>fastboot flash zip firmware.zip
target reported max download size of 1826414592 bytes
sending 'zip' (29494 KB)...
OKAY [ 2.342s]
writing 'zip'...
FAILED (remote: not allowed)
finished. total time: 2.841s

i'v search for my problem around but didnt find any solution for it
any help will be welcomed