So that you can use the adapters they must be activated in the Backend.Config.xml.
There are two steps to be done:
First, there has to be a key value pair for the adapter path. Take a look at the already activated adapters for reference.
<add key="ADAPTER_PATH_<name for the adapter>" value="<path to dll>"/>
Second, you have to add the adapter path to the ADAPTER_PATH_LIST.