LTM8003 run/shutdown problem

Hey

I am using in my design in LTM8003HY.

The pin of the RUN is connected with pull-down to the ground , To active the run pin i need to bring 3.3V form another card.

The LTM8003HY get 28V to the Vin.

Vout is design to supply 12V , and the BIAS pin connected also to the Vout.

My problem is when I am enter 28V to LTM8003HY, and the RUN pin is not connected or i am enter 0V to this pin , I have 5V in the output.

I search in the datasheet more information about the RUN pin but don't find answer about this problem.

How to get 0V in Vout ,when the RUN pin is connected to 0V? 

Additional Information about my design.

When I enter  the RUN pin voltage that greater then 1.1V , I am getting the 12V.

In my circuit i have 3 types of Grounds . The LTM8003HY in place it have only one ground. and don't min with the other 2 types.

I have exposed pads for the TR/SS and Sync pins. i don't have exposed pad for the PG pin. 

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