Message Oracle PLS-00223 - paramaterless procedure string used as function

ERRORparamaterless procedure string used as function
CAUSEAn identifier being referenced as a parameterless function actually represents a procedure.
ACTIONCheck the spelling and declaration of the identifier. Also confirm that the declaration is placed correctly in the block structure. If necessary, change the declaration of the identifier or change the reference so that it does not require a return value.