Please try to change branch id to 002 in "Settings" -> "General"
Why need change of code?
-> Because the ATO assigned a branch on the ABN. Possibly your client has two separate businesses under one ABN.
Failing that, check the following:
A. The ABN is still active.
B. The ABN is correct or That identifier in LodgeiT are correct?
C. Can you able to lodge activity statement bas for other entities?
D. Can you confirm that this entity causing issue is in your ATO portal and has not expired?
E. What period does the BAS relates? ATO is not allowing lodgement for old forms, please lodge via portal.
Note: Branch code will depend on what is recorded in the ATO portal. If you are experiencing the same error, always check what code is recorded in ATO's activity statement.
How to compare LodgeiT code and ATO branch code?
Navigate to ATO portal, click "Lodgements" and select "Activity Statements"
Note, check the ABN and TFN if portal and LodgeiT details are matched.
Below is an example on how the branch code should appear -