Check if the time periods you have in the form are valid for data entry for that scenario. Also if you are using begbalance as a time period in the form, make sure it is enabled as a time period on the scenario member. Also check the data storage type of the members on the form.
If I have any other suggestions I will stop by and let you know. Mean while you check the above issues are not causing the problem.
Also check if the data form is set to Read only.
Thanks for your reminding. I have checked the valid range of time of scenario. Also, the form is editable. And I also checked other as you said.
However, I still cannot input at the parent level. Of course, I got several level 0 members on the form and I can input them but not parent members.
Workflow Tasks are not allowed, and children of target members must be blank for example, #MISSING to enable data input at the top level. Target members must be set to Store (Dynamic Calc overrides data input with sum of children).
Make sure you have refreshed the database from planning.