SAP ABAP : getting syntax error

Hi friends,

doing up gradation

there is one program in ECC 5.0, and it is working fine in ECC 5.0

But while upgrading to ECC 6.0 it is giving syntax error.

below I am sending the code.

BEGIN OF lty_s_ekab_key, "1001282

konnr TYPE ekab-konnr,

ktpnr TYPE ekab-ktpnr,

ebeln TYPE ekab-ebeln,

ebelp TYPE ekab-ebelp,

END OF lty_s_ekab_key.

CLASS lcl_entity_ekab DEFINITION INHERITING

FROM lcl_entity_any.

PUBLIC SECTION.

METHODS: constructor,

if_any_table_mm~read_line REDEFINITION,

if_any_table_mm~read_lines REDEFINITION.

PRIVATE SECTION.

METHODS prefetch

IMPORTING im_key TYPE lty_s_ekab_key

RETURNING value(re_t_ekab) TYPE lty_t_sorted_ekab.

ENDCLASS.

after checking the systax error , i and getting error like lty_s_ekab_key is unknow.

Plz help me to solve in this issue.

Thanks and Regards

Rihan