Custom Recovery wont stick on xoom verizon

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http://forum.xda-developers.com – ive just unlocked the bootloader for my xoom 4g (stingray) and went to install a custom recovery and it flashes fight in fastboot then when i reboot into recovey it shows the green android logo laying down then shows the red ! . i have to hold the power and the up volume key to show stock recovery. why is the custom recovery not sticking. is it because im not rooted? im trying to root this devices and the all in one tool needs to reboot into custom recovery but keeps going into stock recovery.. what am i doing wrong? (HowTos)