企业库5-执行非查询负结果

我使用microsoft enterprise library 5有以下代码:

Database database = DatabaseFactory.CreateDatabase("myConStr");
int rowsAffected = database.ExecuteNonQuery("[DeleteCustomer]", cboCustomers.SelectedItem.ToString());

myConStr在app.config中定义正确(它适用于其他基于EL的查询)。DeleteCustomer SP定义为:

CREATE PROCEDURE DeleteCustomer
  @CustomerID nchar(5)
AS
BEGIN
    -- SET NOCOUNT ON added to prevent extra result sets from
    -- interfering with SELECT statements.
    SET NOCOUNT ON;

    -- Insert statements for procedure here
    delete from dbo.Customers
    where CustomerID = @CustomerID
END

在ExecuteNonQuery metod的文档中,结果被称为返回受影响的行数。

然而,我总是得到结果“-1”,即使删除工作良好。怎么了?如何获取已删除记录的数量?

谢谢, 卢西恩