total value of 2 or more dataset

Hello,

I have one requirement i.e  I have 2 fields which are "A" and "B"

Both are coming from a different  dataset and table  

i want the total of these 

I have used exp =Sum(Fields!new_A,value,"DataSet1")+Sum(Fields!new_B.Value, "DataSet2")

but it is showing wrong value please help 

I am using a crm online version