I'm not able to add accounts into a Net Account

Only the System Administrator has the ability to add or modify a net account.

As a system administrator, when you attempt to add new accounts into an existing net account, ART may not allow you to do so due to one or more of the following reasons:

#1: The accounts you are attempting to add don't share the same attributes and ownership information.

In order to net accounts, each composition account must share the same ownership and attribute information.  Ensure that the ownership and attribute information of the accounts being netted are the same as the existing composition accounts in the net account.  Once the necessary changes are made, go back into the Accounts > Create/Update Net Account menu and to re-net the accounts

#2: The reconciliation for the net account has already been started for the period.

If the Preparer has already started work on this net account, you will not be able to modify the net account.  There are two options if that's the case:

1. Reset the status of the net account back to Not Started.  Then, System Admin will be able to modify the net account in the Accounts > Create/Update Net Account menu.  

Caution: Upon resetting the account, all work performed in the reconciliation, as well as sign-off information, will be removed. Preparer and/or Reviewer should be appropriately consulted prior to System Admin resetting the account.

2. System Admin can opt to modify the net account in a subsequent period, where work has not yet been started for the net account.

#3 The accounts that are being netted do not exist in the current period.

The first period in which the accounts are loaded is when they are eligible for netting.  So if you uploaded new accounts in current period, then those new accounts cannot be netted in a previous period.  To verify which period the accounts in question were created, go to Accounts > Account Profile Update to search for the accounts and check the Creation Period field.