AutoInvoice Error: ORA-01400: Cannot insert NULL into [Table Name]

R12 AutoInvoice Error: ORA-01400: Cannot insert NULL

Errors:
1) arccmm() ORA-01400: cannot insert NULL into ("AR"."RA_CUST_TRX_LINE_GL_DIST_ALL"."CUST_TRX_LINE_GL_DIST_ID")

Reason:
Missing triggers on RA_CUST_TRX_LINE_GL_DIST_ALL table:

AX_RA_CUST_TRX_LINE_GL_ARDI1
AX_RA_CUST_TRX_LINE_GL_ARU1
AX_RA_CUST_TRX_LINE_GL_ARU2
RA_CUST_TRX_LINE_GL_DIST_BRI

Steps:

1) Run this select to check if this is the case:

select status,trigger_name,trigger_type
from all_triggers
where table_name ='RA_CUST_TRX_LINE_GL_DIST_ALL';

2) Enable Trigger by running
ALTER TRIGGER RA_CUST_TRX_LINE_GL_DIST_BRI ENABLE;
ALTER TRIGGER AX_RA_CUST_TRX_LINE_GL_ARDI1 ENABLE;
ALTER TRIGGER AX_RA_CUST_TRX_LINE_GL_ARU1 ENABLE;
ALTER TRIGGER RA_CUST_TRX_LINE_GL_DIST_BRI ENABLE;