Getting error as 'BD' cannot be converted to number

I am using the for iteration with condition i am getting the error .

Could you please help me with the same?

Here is the syntax for the same.

DATA(lt_final_data) = VALUE tt_product_price( FOR <fs> IN it_pr_aps_data
( zgta_country_id = COND #( let t = VALUE #( it_pr_aps_data[ <fs>-zgta_country_id ]-zgta_country_id ) in
WHEN t is INITIAL
THEN t
when t is not INITIAL
then
VALUE #( it_gex047it[ ziso_country_code = <fs>-zgta_country_id ]-zgta_country_id_1
DEFAULT ' ') )

What i am doing wrong here?