The XML for the ribbon is case sensitive, you must follow the exact casing
used in the ribbon docs. You also don't use a <tabs> or a tag attribute or
some other things.
One last question. Now that I've added my button to the Send to menu. Is it
possible to have the little description text that appears below the other
button on this menu? I tried screentip and supertip but they don't do the
trick.