Regarding the behaviour of LDO ADM7150

i am using LDO from analog devices ADM7150 to generate the output of 5 V from an input supply of 12V. Enable pin is parmanently connected to 6V by using a divider circuit at input supply. I am using this circuit exactly in same manner as given in data sheet.

I am using this 5V to operate the 2 VGA circuits AD600.to amplify my signal.. I am facing the problem that LDO become off sometime at power on and sometimes it power on normally. i am drawing not more the 80 mAamp current from this. 

Can any one tell me that what mistake i am doing or any other suggestion ti correct my circuitry.

Renu Saini

DRDO