Apply Credit Memo API return error with 'The installment Number is null'

hi guys,

Currently I try to make API for credit memo and apply but, it returned with error 'The installment  Number is null".

Anyone knows how's the error from :

API:

DECLARE

  K_api_version   CONSTANT NUMBER := 1;

  K_init_msg_list CONSTANT VARCHAR2(1) := FND_API.g_false;

  K_comments      CONSTANT ar_receivable_applications.comments%TYPE := 'API CM';

  K_commit        CONSTANT VARCHAR2(1) := FND_API.g_false;

  l_acctd_amount_applied_from ar_receivable_applications_all. acctd_amount_applied_from%TYPE;

  l_acctd_amount_applied_to   ar_receivable_applications_all. acctd_amount_applied_to%TYPE;

  l_cm_app_rec                AR_CM_API_PUB.cm_app_rec_type;