Qty difference in goods issue and goods receipt in STO

I am using STO for transfer of goods from one plant to another plant using movement type 351.

The material (sand) that is transfered is with UOM as Ton. There is always a difference of issue qty and received qty by few kgs because of the nature of material. If the qty received is less than the issue qty than there is no problem but when the qty received is more than the issue qty, the system is not permitting the goods receipts.

How to handle this.