Just to clarify here.
Your edited O.pbo should be placed in the OFP original Dta folder. WrpEdit will see it ok, but, before running OFP, rename it or remove it somewhere that is not in OFP's file path. Alternatively, you can rename it temporarily.
Remember to reverse whichever procedure you carried out when you want to continue editing your island in WrpEdit.
i.e. Put it back, or rename it back to O.pbo.
Failure to do this will result in WrpEdit complaining that it can't find any of the objects from O.pbo that you may have added to your island.
Another point,
The original O.pbo must NOT be moved elsewhere, it lives in the Res\Addons folder.
If you have moved it elsewhere, put it back.
It MUST be named O.pbo, if you have renamed it to something else, rename it back again.
Hope this helps.
Planck