Issue while assigning summary calculated item to db item when-remove-record

We have Master and Detail Blocks

We are assigning summarized control item in the detail block to a database item in the Master block. Whe are assigning this
when validating detail block reocrd. The Master block item is getting changed when we insert/update in the detail block.

The issue is, master block item is not getting updated when i delete record in detail block. Then i used when-remove-record trigger
in the detail block, but this is also not assigning data.

below is the block of code pertaining to when-remove-record

begin

:pms_contracts_all.net_price := :pms_billing_types_all.total_net_amount;