Im only using it for my group to heal. But if the target frame works the same way here is what I have done to heal my group.

The group is in a separate frame (ofcause - sorted alphabetically).

I have bound a macro in Vuhdo, by draggin the macro to the designated button in Vuhdo.

I found out, after alot of fiddeling around, that if you update your healing macro, and NOT drag it to the button again, Vuhdo won't update the macro correctly. I spend maybe 1 hour before I figured this out.

So try and redrag the macro to the button you want to use..... maybe it will help?

EDIT: Also, try to look here, theres a neat guide to help out in general:
http://vuhdo.ithato.com/VuhDo+User+Manual&bl=y