bind to a boolean always returns false

[dennis....@mphasis.com]

on Stardog free version 3.1.4

this query (something like it):

Select ?A ?S ?P

{

        ?A ans:has ?S .

        bind ( EXISTS { ?S a* ans:oS } as ?AoS ) .

        Optional { ?S ans:SoS ?P . }

        bind (EXISTS { ?P a* ans:oP } as ?SoP) .

        Filter ( ?AoS || ?SoP)

}  

fails in stardog - ie no rows

but returns two rows in Jena

because  ?AoS and ?SoP are both false in Stardog, but one is true in Jena, which it should be. 

I couldn't come up with a logically equivalent expression to do this in Stardog Sparql.