Microsoft Provider for Oracle and Positional Parameters

Is there a way to use positional parameters when calling an Oracle stored procedure using System.Data.OracleClient?

Parameter IDataParameter = dbCommand.CreateParameter (),
parameter.Value = "Blah Blah",
parameter.Type = OracleType.Varchar;
dbCommand.Parameters.Add (parameter);

The above code creates a parameter and names it "Parameter1". When the stored proc is called by Oracle, an "wrong number or types of arguments" error appears.