You can't load ODOL p3d models into Oxygen, you need MLOD p3d models.
This is why Oxygen won't load the p3d, it is probably an ODOL p3d.
The p3d's that came with the original demo version of OFP are MLOD. These will load into Oxygen.
Not all current ODOL p3d's are available in MLOD versions however.
The demo version p3d's are available somewhere on the net, but I don't have the link, maybe someone else can provide that for you.
Or use the search functions on this site, you might find a thread somewhere that provides this information.
Planck