AX 2012 - My New Field's Value Disappearing when Editing VendInvoiceInfoTable

I add a new field to VendInvoiceInfoTable When try to edit with VendEditInvoice form I saw my new field's value is empty. After a long research I found out Axapta copy source record to another record and edit this new record. Meanwhile Axapta skips my new field. Axapta uses table method copyFromHeader while copying. Add my new line:

    this.VendorRequestedWorkerEmail = _header.VendorRequestedWorkerEmail;
    //my new field
    this.myNewField     = _header.myNewField;

Problem overed. Same method valid for related VendInvoiceInfoLine table too.