操作插件不能删除分录行功能

我准备实现的功能是：点“保存”按钮时，明细信息里批号字段为空的会被删掉
代码如下：
public override void BeforeExecuteOperationTransaction(BeforeExecuteOperationTransaction e)
{
//------------
foreach (ExtendedDataEntity extended in e.SelectedRows)
{
DynamicObject dy = extended.DataEntity;
DynamicObjectCollection docPriceEntity = dy["SAL_OUTSTOCKENTRY"] as DynamicObjectCollection;
DynamicObject doPriceEntityItem = null;
int iAllCount = 0;
iAllCount = docPriceEntity.Count;
for (int i = 0; i < iAllCount; i++)
{
doPriceEntityItem = docPriceEntity[i];
if (doPriceEntityItem["Lot_Text"]==null)
{

docPriceEntity.Remove(doPriceEntityItem);
}
}
}

运行时没有报错，但是单据中数据行没有被删除，这是为什么啊？
求指点