WCF - dealing with concurrency

Hi,  guys, how are you?

I have a WCF built with PB.NET and a PB 12 classic client.

when I have multiples calls of the wcf, I got some database errors, like ora-24334. It seems that all the instances use the same SQLCA transaction.

We have tried some configurations inside the project (service attribute and operation atribute) like InstanceContextMode and the ConcurrencyMode.

Is there any specific configuration we have to do here?

We have tried PerSession, PerCall and Single, along with Single, Re-entrant and Multiple, but without succes.

Everything runs fine when we call the service only once....

Also we have  threadsafe =yes for database connection.

By the way, we are using oracle 10g. Can anyone give us some help, please? Thank you!