Tax amount is not populating in service contracts

i have used the oks_import_line_pub.update_contract_line api for populating tax amount using tax classification code.

Api return status is 'S' but its not populating the tax amount.

Script is below:

/* Formatted on 2017/01/03 18:25 (Formatter Plus v4.8.8) */

DECLARE

   ln_service_line_id          NUMBER

                                   := p_line_id;

   ln_contract_id              NUMBER                                := p_contract_id;

   lt_line_tbl_in              apps.oks_import_line_pub.line_tbl_type;

   lt_line_rec_in              apps.oks_import_line_pub.line_rec_type;

   xt_line_tbl_out             apps.oks_import_line_pub.line_tbl_type;

   ln_api_version     CONSTANT NUMBER                                 := 1.0;

   lc_init_msg_list   CONSTANT VARCHAR2 (10)          := apps.okc_api.g_false;