SAP Message W8074 - Element & cannot be read with structure &

Diagnosis
Element &v1& is in the container as a character string.
Structure &v2& is for reading element &V1& (via binding definition orsetting parameters of expression evaluation). But, structure &v2& isnot purely character string-based (does not contain only fields of theinternal types CNDT). Therefore, element &v1& cannot be read withstructure &v2&.