iBATIS's SqlMapper.Update method is returning -1

I'm new to Oracle and iBATIS. I have an update procedure in a package in the DB. If I call the Update method of an SqlMapper object to execute this procedure, the procedure runs properly (I can see the new values in the database).

However, despite the fact t开发者_StackOverflowhat the iBATIS documentation states that the Update method should return the number of rows effected by the UPDATE call, the method returns negative one (-1) under all circumstances.

Does anyone know what's wrong? I'm using the .Net iBATIS library.