I have a SQL Server 2012 where all databases are set up in instances.
I created a DTS package that accesses a table in a database, let's say
MyDB\MyInstance and CSV files in a network folder.
Integration Services is NOT running in an instance.
My domain account doesn't have rights to login to Integration Services, so the DBA used his account and deployed the DTS package to Integration Services MSDB relying on the package for access and it runs from there without any issues. The DTS package uses my domain account to login to the database and access the table.
Then I created a SQL Job to run the package. It didn't run, of course. I create a proxy account to run the package. The proxy account uses the credentials of my domain account (which doesn't have access to SSIS, but the DBA temporarily made it a local admin on the SQL Server assuming that would give it the rights that it needed but that didn't work either. The error message states that it can't access the Integration Services database.
We gave the proxy SQL Agent operator role so we run the job with it.
The account running the SQL Agent for the instance is NT
I don't know what else to try.
If there's any information missing please let me know. I apologize, there are a lot of moving parts.