Remove Line on UDO

I'm working with a UDO with a matrix.  I know SAP doesn't automatically create a new line in UDOs, so I have a macro that automatically calls activate(UDO1_Add_Line); and that works fine.  However, when I'm ready to Add the document, I wanted to remove any blank last line.  When I call Activate(UDO1_Remove_Line), I get an error saying that menu item is disabled.  I can manually right-click and click Remove Line.  Do I need to call a Focus() command beforehand?  Or does this functionality not work within B1Up?