hmm,try it again,then reboot your phone before relocking the bootloader. try and adb reboot recovery
back to recovery and see what happens.
if its still twrp,copy/paste your entire cmd window,and let me see a screen shot of your adb/fastboot dirctory
last,and not least,upload or link the recovery you used and ill see if it will flash to my phone.
failing all that,see if you are able to change from twrp to clockwork,using the same process.
off to work,ill try and watch but it may be later this evening before i can reply.