loop inside loop with fieldsymbols

in my logic field symnol data is not mapping correctly .

field symbols overwriting with new values.

please provide me solution .

SELECT * from  z30lo_t001w

     INTO CORRESPONDING FIELDS OF TABLE  lt_tkey.

   if lt_tkey is not INITIAL.

     LOOP at lt_tkey ASSIGNING <ls_key>.

        <ls_key>-STORE_INTERNAL_ID =  <ls_key>-werks.

** update  internal store id

      LOOP AT <ls_ref> ASSIGNING  <ls_ref_line>.

           <ls_key>-STORE_INTERNAL_ID = <ls_ref_line>-store_internal_id .

                ENDLOOP.

     ENDLOOP.