Statechart Checks : (C15009) Elements unnecessarily defined as double-buffered

(C15009) Elements unnecessarily defined as double-buffered

There are Elements that defined as “Double Buffered” in their Design-Attributes unnecessarily.
Error In:
Design
Example:
Data-Item DI1 has its Design-Attribute “Double Buffered” set to “yes”, but it is not used with any of the operators tr(), fs() or ch().
Erroneous Elements:
Data-Items and Conditions