Ok, so now I understand. You are not understanding what a Dynamic form rule does. It only kicks in when an individual record is in edit mode. It does not affect anything when the record is not being edited.
If you need a field to change based in the value of other fields when the record is not being edited on a Form, then you need to use a formula field. If the reason that you are not using a formula field is that you need to control the sort, you will need to fall back on results which are numbered. For example,
1.Open
2. in Process
3. Complete
