Your layout shows a portal--which may have a specified sort order.
Could you export this data from the context of the portal's table instead of the layout's?
See if you have a portal sort order specified. If so, temporarily remove that sort order and see if what you see in the portal matches your exported order. If so, try specifying the sort order on the relationship instead of in portal setup...
Hello PhilModJunk, thank you for your answer! The problem is solved after unchecking the "sort" option in the table setup dialog box.
There is another problem that i forgot to mention in my post above. I just uploaded a new picture. Please look at it. The second and third data records in <c_names> are in wrong order whether i check or uncheck the "sort" option of the table. The feature of this "c_names" column is that a new layout is opened after clicking a name data.
What caused this problem? Has anyone experiences about it?
I am not sufficiently familiar with xml exports to offer a suggestion. If no one else chimes in, you may want to try this question in TechNet.