The documentation of the Mockito and Dexmaker projects does not seem to clearly state the relationship between the two, they only make mention of each other. If Dexmaker is required, which versions of Mockito and Dexmaker are compatible?, and is only the dexmaker-mockito artifact required?
You need the latest version of mockito (at the moment 1.9.5), as seen in the main documentation §28. Mockito offer a way to have a different bytecode engine, that dexmaker-mockito provide if it's on the same classpath. (Indeed the wiki is a bit outdated there but it states you need both jars).
Hope that helps.