WD Java -BuiltIn Type or Simple Type expected

Question

Hi,
As part of ECC upgrade we reimported RFCs into WD from new ECC system. We have 6 DCs and created 6 separate activities.
Except one activity, rest of all activities got activated and released. For one DC, I got error BuiltIn Type or Simple Type expected while activating activity.
Hence I followed the instructions as explained in below thread by creating new activity added local files into DTR. When I release this new activity, I got
"Activity Containing only folders are not considered for activation and transport". and pending activity got activated without any error hence I released.
https://scn.sap.com/thread/1523050
What does mean of the message? 
One more question is, while I did the same check for rest of DCs whether any files available locally or not, I found some of the files showing in local in each DC. So, is these local files will create any issues in future WebDynpro changes or creating / activating activities.
Please advise the better approach to fix these issues permanently.
Thank you,
Ian

Answer 1

if it is activated in nwdi, i think those dc are in good shape.
if you don't know wd dc structure and what should be checked in, you just compare the failed one with the good one, then you should know what is missing