Either your Acrobate Reader oleobject is not installed properly or it's an old PB 11 bug.
When you go to select the Ole object can you see this :
Try to reintall theAcrobate reader or try to insert the OLE control Adobe and use
ole_3.object.loadFile ("...doc.pdf")
In my case both work fine but I am using PB12.5.
Regards.
Abdallah.