Are both Alfresco systems of the same version? Parts of the public ReST API are still being evolved and some operations/resources may not be available in all 5.2 versions (e.g. there were some additions in 5.2.1 - 5.2.3 Enterprise releases).
As an aside: ACS 5.2.x provides the new public REST APIs and is also the baseline for future ADF-based applications. In short, ACS 5.2.x is the "best" release so far (well, at least until ACS 6.0.x goes GA in the next month or so) ... yes, I know, I'm biased.
So, this might be a great time to work with your Alfresco Enterprise sys admin to plan an upgrade from 5.0.0 to 5.2.3. I'm sure Alfresco Support will provide advice, as needed.