Aggregate Records - Sum

Aggregate Records - Sum

What I'm trying to take the sum of total earnings and have that put into a field called Actual Earnings. But i keep on getting this error.
 
On Success
 
      Actual_Earnings = Business_Plan[Recruiter == input.Recruiter].sum(Earnings);
 
And this is ther Error message:
      Error at line: 1
      Variable "Recruiter" is not decleared