If Webtop is installed before DAB, you may experience the ucf-server-api.jar issue referring to different location, the one in DAB. The reason is that, dctm.jar ->manifest.mf has the following:
Application%20Builder/devws.jar
And devws.jar ->manifest.mf has ucf specified as below. This jar is in C:\Program Files\Documentum\Application Builder, the ucf-server_api.jar is under C:\Program Files\Documentum\Application Builder\lib
To resolve this: Change the classpath