Tribunal held that revision is held to be valid , however, the working made by the Principal Commissioner regarding the excess set off of loss pertaining to the assessment year 2009-10 alleged to be wrongly allowed by the Assessing Officer was not correct and this matter should have been left open by him to the Assessing Officer for making the working on the basis of actual loss pertaining to the assessment year 2009-10 as determined in the relevant assessment.( AY.2015-16)