Another shameless cross-post from the Keil forum:
http://www.keil.com/discuss/docs/thread1630.htm

When building a uVision Project, it seems that the order of the files within a Group, and the order of the Groups within a Target matters: the build process always examines the files in order as they appear within the Group, and the Groups in order as they appear within the Target.

So, If I need to add file(s) and/or Group(s), how do I get them into the right order?

Similarly, how can I re-order files and/or Groups if this becomes necessary?

I'm using uVision v2.23.