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) A socialist is someone who will give you the shirt off *someone else's* back.