Any chance that either or both "TransferToCostCenter" and "TransferFromCostCenter" are NULL?
Not equal won't work on NULL; you'll have to explicitly allow for NULL in the comparison.
For example:
WHERE ...
AND ISNULL(INSERTED.TransferToCostCenter, '-1') <> ISNULL(INSERTED.TransferFromCostCenter, '-1')
SQL DBA,SQL Server MVP(07, 08, 09) "It's a dog-eat-dog world, and I'm wearing Milk-Bone underwear." "Norm", on "Cheers". Also from "Cheers", from "Carla": "You need to know 3 things about Tortelli men: Tortelli men draw women like flies; Tortelli men treat women like flies; Tortelli men's brains are in their flies".