Sales order unable to create Invoice

Summary:

where the sales order is created.

scenario 1 : where the unit price for an item is "100 SAR" and the price is manually Price adjusted in the line as "0 SAR" and proceeded further then invoice is created.

scenario 2 : where the unit price for an item is "105 SAR" and the price is manually adjusted in the line as 0 but while creating the invoice for the Sales order it not getting created where are getting error( The transaction created can't have a negative amount because the creation sign of the transaction type is positive.)

as i raised an SR they found out that