Multi event Trigger syntax
According to the manual, "If multiple events are specified, the triggered action must be a compound SQL (compiled) statement (SQLSTATE 42601)".

BEGIN ATOMIC indicates an inlined compound SQL statement. You'll have to replace it with BEGIN to make it compiled.

It might be worth noting the difference between the inlined and compound SQL in case of a trigger. An inlined compound statement becomes part of the triggering statement execution plan, while the compiled compound statement is invoked much like a stored procedure would be, with the associated overhead. Subsequently, triggers with inlined statements might perform a bit better, which may become noticeable on a heavily loaded system.