Message Oracle ORA-54553 - incorrect geometry for appending

ERRORincorrect geometry for appending
CAUSEThe geometry could not be appended to a homogeneous collection (for example, multi-geometry) or to a heterogeneous geometry (for example, collection). In other words, the gtype of the geometry to be appended was neither GYTPE_COLLECTION or GTYPE_MULTI-X (where X is point, curve, surface, or solid).
ACTIONEnsure that the geometries involved in the append operation have appropriate gtypes.