HI Mohanraj,
I have to do this in a multisource universe because I have the "report database" (whit the info about creation date, request user ecc...) in a Oracle schema.
The log function with the trigger I wrote before is in a SQL Server schema.
I don't know why we didn't develop all in a single database but I suppose that who developed this custom function had strong .net a and t-sql experience vs a basic knowledge of java/plsql.
Now I'm thinking about a LINKED SERVER so I can create a single source universe and I can go ahead!
thanks a lot for your help