when update, delete "Pay Schedule valid" record, pay schedule is auto validate, but when new record user must manual run validate

Triaged by Diego Ruiz,

Still reproducible in 7.1z. After discussing with Carlos, changed from improvement to Bug and minor to Major.

It does not validate on create as mentioned by Hiep, and this causes that when there is already a valid Payment Schedule if you add an additional line with an amount != 0, the Pay Schedule is not valid anymore, but the parent record is checked as valid until the Validate button is pressed. I think the behavior should be consistent in all the CRUD actions.