Append to Datalist

Hello,
I have a DataList which I fill up with colors and a number. The problem is that in some way he sorts without any logic (in my view). Something like this:
1. black green yellow
3. green red blue
5. blue yellow brown
...
10. brown blue red
11. red blue brown
2. black green brown
4. black brown blue
The colors are added with comboboxes. So the users selects 3 colors and then hits a button. I want it each time to append at the list, so without sorting. So the last one added should always be at the back. How can I do this?
I didn't put anything from sorting in my code, he just does it automatically. Do I need to switch this off or something?
Thanks for help.
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