mobile

I'm trying to update to either official LP or AOSP lollipop, but trying to flash a zip with recovery just ends in errors with all the zips I've tried to flash with both clockwork and Phil Whi Touch, some zip files fail because of bad footer, some actually say "installed sucessfully" and then just reboot in to my old 4.4.4 setup.
Is this due to a locked bootloader?

I actually can flash ROMS using Sony Mobile Flasher but I've only found the 4.4.4 stock D6603_23.0.A.2.93_Generic GLOBAL.ftf file and not a LP version.

Any Ideas where to go from here?