I had a very similar problem. I was adding several rows to different tables within a transaction using LINQ. Within the transaction scope I was calling a function which accessed the SQL server (not even the same database, but the same SQL server). When I attempted to execute the transaction I got the same error you are getting. I moved the code that accessed the database outside the transaction scope so that I retrieved the value to a local variable, and, voila!!, the error went away.