[Q] Why does clockwork block recovery mode?

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http://forum.xda-developers.com – I have done adb reboot bootloader my bootloader is unlocked but here is where it gets weird for me... I am trying to install SuperSU-v0.87.zip and it says Use the volume keys to highlight Recovery Mode, Use the power button to select it. which is easy enough, but when I do this I get an android with a triangle and exclamation mark... which blocks me from the next progression; Once in recovery, select Install zip from SD Card Select choose zip Choose SuperSU-v0.87.zip, then select yes to install If I press vol. up and power I get clockwork screen but cannot access defaul (HowTos)