Hi Raja,
You can should use smallest unit of measure as base unit of measure like gm (gram) and alternative or unit of issue should be KG. In you case base unit of measure as TO and issue unit of measure as KG this not recommended by SAP.
Also please check enhancement XMRM0001 on transaction SMOD EXIT_SAPLBARM_001 Customer Exit: RM_BACKFLUSH_CHECK.
Also refer OSS note 565762 - MFBF: Backflush quantity not checked for decimal places
Regards,
R.Brahmankar