Feel you have not read all the messages given here. Read all the posts.
Also, whats your requirement?? Have you tried using Permit Functionality instead of going for development??
Usage of Permits in SAP Plant Maintenance
If you want to check the planned cost, you should have saved the order. Only in change mode, I think you can able to get the planned cost.
Check with your ABAP consultant on getting these values before saving the order.