Semantic Error (SEM1134): The assignment of function blocks is not supported.

In ST code, a complete function block instance is used in an assignment statement.
Function blocks cannot be assigned like variables although they are declared in the same way as local variables ('Usage = Local'). Only the formal parameters of an FB POU can be used in this way, as they are "normal" variables.

Error example: possibly, your intention was to transfer all instance data from one instance to another instance of the same FB as shown in the invalid ST example.