Problem with shortcut for sub-beaming

Can anyone else verify this?
I can have a group of sixteenth notes, and some middle note can be selected. Then, in the beam properties palette I can double-click sixteenth-sub-beam (the fourth from the left) and get that look to work, but if I set up a shortcut in preferences->shortcuts for "Beam 16th sub" -- I've tried multiple key combinations -- and utilize that shortcut, it doesn't work! Am I the only one having this problem? Yet the regular Beam start and Beam middle shortcuts work just fine for me. This also doesn't work for the 32nd sub-beam either (the shortcut: the palette option works just fine).