The prerequisite to using Unx Documenter is to have Semantic Layer Java SDK enabled. However it is not enabled during default installation of SAP BusinessObjects client tools. Here is how you can enable it:
Open Program and Features.
Find the client tools and double click on them (or right click and select Uninstall/Change)
Click Next on language selection. Add Semantic Layer Java SDK and complete installation with Next.
You are ready to go.