Diagnosis
You want to create a sub-item. In doing this you entered a quantitywith a different +/- sign from that of the quantity in the superioritem. However, all sub-items have to have the same sign as the quantityin the superior item.

System Response
The system does not create the sub-item.

Procedure
Change the +/- sign or cancel processing of the sub-item.
You can enter both positive and negative quantities for a material asfollows:
Create a second item for the material in the BOM with the oppositequantity sign.
For both items, only create sub-items with the sign of the superioritem.