a syntax mistake about too6 table.

hi,everyone.

I'm studying WD4A recently,and do an exercise imitating the example in chapter 4,but I meet a problem when coding a method named convert_values(), this method belongs to the model component ZEXP_CONVERSION_MODEL.

the source is below:

method CONVERT_VALUES .

DATA ls_conv TYPE if_componentcontroller=>element_conversion.

DATA lr_input_node TYPE REF TO if_wd_context_node.

DATA lr_sub_node TYPE REF TO if_wd_context_node.

DATA lv_fromunit TYPE too6-msehi.

DATA lv_tounit TYPE too6-msehi.

DATA lv_value TYPE string.

DATA lv_denominator TYPE f.

DATA lv_numerator TYPE f.

DATA lv_nomout TYPE dzaehl.

DATA lv_denomout TYPE nennr.

DATA lr_node TYPE REF TO if_wd_context_node.

lr_input_node = wd_context->get_child_node( 'UNITS' ).

lr_input_node->get_attribute( EXPORTING name = 'IVALUE'

IMPORTING value = lv_value ).

lr_sub_node = lr_input_node->get_child_node( 'FROMUNIT' ).

lr_sub_node->get_attribute( EXPORTING name = 'UNIT_INT'

IMPORTING value = lv_fromunit ).

lr_sub_node = lr_input_node->get_child_node( 'TOUNTIT' ).

lr_sub_node->get_attribute( EXPORTING name = 'UNIT_INT'

IMPORTING value = lv_tounit ).

CALL FUNCTION 'CONVERSION_FACTOR_GET'

EXPORTING

no_type_check = 'X'

unit_in = lv_fromunit

unit_out = lv_tounit

IMPORTING

denominator = lv_denominator

numerator = lv_numerator

EXCEPTIONS

conversion_not_found = 1

overflow = 2

type_invalid = 3

units_missing = 4

unit_in_not_found = 5

unit_out_not_found = 6

OTHERS = 7

IF sy-subrc <> 0.

RETURN.

ELSE.

CALL FUNCTION 'CONVERT_TO_FRACT10'

EXPORTING

nomin = lv_numerator

denomin = lv_denominator

IMPORTING

nomout = lv_nomout

denomout = lv_denomout

EXCEPTIONS

conversion_overflow = 1

OTHERS = 2.

IF sy-subrc <> 0.

RETURN.

ELSE.

ls_conv-cvalue = lv_value * ( lv_nomout / lv_denomout ).

ENDIF.

*---- Supply node with data

lr_node = wd_context->get_child_node( 'CONVERSION' ).

lr_node->bind_structure( new_item = ls_conv

set_initial_elements = abap_true ).

ENDIF.

endmethod.

and the mistake is:

Method CONVERT_VALUES Field "TOO6-MSEHI" is unknown. It is neither in one of the specified tables nor defined by a "DATA" statement

can anyone settle my problem?

how to specify tables in dynpro component?