CRM 2011: the value of field on parent entity not updated

Hi All,

I have 2 custom entity, ex: headerEntity & DetailEntity.

in headerEntity I have one field "total" = (currency) which updated by records from detailEntity.

I use plugin, and trigger when update value in detailEntity it would update to field "total" in headerEntity.

what I am asking is after updated the value in field "total" not update in form, I need close the form/page and open again, even if I just refresh the form/page there is still show old value.

please advise.

thanks.