What you seem to be experiencing is the effect of the duplicate content filter. To ensure diversity in the SERP Google will typically filter all but the canonical version of a document. In this case, the syndicated article published by the aforementioned publisher is ranking higher, and due to this, it has been selected as the canonical.
If you build sufficient links to another instance of your article it will take over as the canonical. When you syndicate your articles you put each republished page into competition for the preferred canonical. The page that is promoted the heaviest is typically the one that avoids the filter and is selected as the canonical.
This is, in part, why article syndication can be so effective. You create a competitive market for the canonical version of your article, which leads to more promotional activity as each publisher competes to be the canonical version. Of course, this all breaks down when the publishers fail to provide attribution back to you.
