Trigger Error

[ramkrish72]

Hi All,
I'm having a problem with a trigger.This trigger is used to write details in to audit tables whenever there is an update of this table-usr_profile_dtl.
the name of the audit table is usr_profile_dtl_aud
trigger name is TR_PRE_UPD_USR_PROFILE_DTL
please find enclosed the attached trigger as below.The problem here is there are 2 environments here one is development and other one is SIT.In devmt it is working fine but in SIT the error messages is as stated below.
The error states that it cannot insert NULL into this table "USR_PROFILE_DTL_AUD"."AUDIT_USER_ID"(it's a before update trigger)

The error message is as follows:
[28 Jul 2004 15:59:57,122]ERROR (UserProfileData.java:changePassword:3623) - ORA-01400: cannot insert NULL into ("MRM2".
"USR_PROFILE_DTL_AUD"."AUDIT_USER_ID")
ORA-06512: at "MRM2.TR_PRE_UPD_USR_PROFILE_DTL", line 6
ORA-04088: error during execution of trigger 'MRM2.TR_PRE_UPD_USR_PROFILE_DTL'

java.sql.SQLException: ORA-01400: cannot insert NULL into ("MRM2"."USR_PROFILE_DTL_AUD"."AUDIT_USER_ID")
ORA-06512: at "MRM2.TR_PRE_UPD_USR_PROFILE_DTL", line 6
ORA-04088: error during execution of trigger 'MRM2.TR_PRE_UPD_USR_PROFILE_DTL'

Any body have any idea of how to rectify this error.Any advice would be great.
Thanks,

[OracleDoc]

What's the difference between a Primary Key and a Unique key? Get that answer and you will have solved your problem