UNIQUE-ALWAYS USED getting an error while Create single invoice

Hi Team,

I am trying to create the transaction for credit memo using AR_INVOICE_API_PUB.create_single_invoice but getting Unique always even populating the customer trx id which it is not available

Could you please let us know what is the issue

below is the script

DECLARE

   

  

l_return_status                VARCHAR2(1);

l_msg_count                    NUMBER;

l_msg_data                     VARCHAR2(2000);

l_batch_id                     NUMBER;

l_cnt                          NUMBER := 0;

l_count                         NUMBER := 0;

l_batch_source_rec             ar_invoice_api_pub.batch_source_rec_type;

l_trx_header_tbl               ar_invoice_api_pub.trx_header_tbl_type;

l_trx_lines_tbl                ar_invoice_api_pub.trx_line_tbl_type;