Aggregate and Non Aggregate in IF Statements

Hi All,

I will get my head around this eventually, however I am stuck trying to make this formula work, I have tried all different types of combinations, taking the SUM off, adding it in etc. However I cannot get rid of the Aggregate and Non Aggregate error message. Any help with this would be much appreciated.

Heres the formula

IF[REGION] = 'REGION A'

THEN ([Margin Deficit])+SUM([Unit Conversion Amount Required]*[New Region Price])

ELSE ([Margin Deficit])+SUM([Unit Conversion Amount Required]*[New Price])

END

Many thanks

Chris