C# EntityQuery OrderBy附加筛选。WCF Ria

我有以下代码来创建entityQuery以加载我的实体：

if (filterExpresion != null)
{
    riaQuery = riaQuery.Where(
        Expression.Lambda(
            filterExpresion,
            Expression.Parameter(typeof(TEntity), "item") // NOI18N
            ) as Expression<Func<TEntity, bool>>
        );
}

if (OrderBy != null)
{
    var orderByExpression = 
        Expression.Lambda<Func<TEntity, int>>(
            OrderBy, 
            Expression.Parameter(typeof(TEntity), "item")
        );

    riaQuery.OrderBy(orderByExpression);
}

为什么OrderBy不应用于查询？

OrderBy返回结果

IOrderedQueryable

。改为：

riaQuery = riaQuery.OrderBy(orderByExpression);

riaQuery = riaQuery.OrderBy(orderByExpression);