Dependend Demand, did not been supplied by other location

Hello,

Would like to ask help on our issue in our product, we have a product on a location which has dep demand, and it was not been supplied by the other location which supposedly to supply it. Below are the details of the issue.

Plant on the Tlane;

From: 0001 to 0010

From: 0010 to 0020

we have dep demand on plant 0020 for 1200 PC, it must be supplied by plant 0010 but the stock on hand on it was 100, so in planing book in plant 0020 distreceipt (confirmed) 100 from 0010 and distreceipt (planned) 1100. so since plant 0010 was not enough to accomodate the depdemand of 0020, we expect that plant 0010 stock deficieny to supply the dep demand will order take stock on the next plant 0001 but in the planning book for plant 0010 no distreceipt (confirmed) and distreceipt (planned) that comes from plant 0001 for the dep demand. what are the possible root cause of this? and where should we look to.

Thanks