Message Oracle PLS-01455 - The predicates IS NULL and IS NOT NULL are defined only for column specifications

ERROR	The predicates IS NULL and IS NOT NULL are defined only for column specifications
CAUSE	The predicates IS NULL and IS NOT NULL are defined only for column specifications, not for any other expressions. Section 5.15, , indicates that in the predicate x IS NULL, x must be a column, and may not be any other kind of expression.
ACTION	None