Hi, Can any one say why the source document field of refund invoice is empty.

Senario: I created a sale order and i confirmed it, following it I created invoice and due to some cause i refunded invoice. When i click on refund invoice it created sales refund journal, but what i noticed is that Source Document(origin) field of newly created refund invoice is Empty. In my view it has to be the value assigned with the Invoice number for which refund is created.

Can any one let me know why this not happened or is there any configuration need to be done to achieve this.