In the case of your 'Dog License' button, each of your layers (static & mouseover) had different links in the Web Properties. The only layer that must have a link is the static layer. In your case, that would be the 'popupServices' layer. If the button element groups on the two layers are soft-grouped, and a link value is assigned, then Xara Web Designer assigns that link to both layer groups.

single-level navbar creation sequence
  • build one button's static group (assume centered text)
    • create shape on static layer (MouseOff, for example)
    • create overlayed center-justified text
    • select both items and center-align (selection bounds)
    • combine them into one group with Ctrl+G
  • build one button's mouseover group (assume centered text)
    • with group selected, Ctrl+K (clone)
    • select mouseover layer in Layer gallery
    • click the move button at the top of the Layer gallery
    • edit the mouseover elements as required for visual effect
  • finish the single button
    • select both the groups (on two layers)
    • Arrange > Apply soft group
    • assign a repeating object name (i.e. repeating:buttonName)
    • assign a valid link at Web Properties > Link (tab)
  • duplicate the button, as needed using any of the following methods
    • Ctrl+C & Ctrl+V (copy & paste)
    • Ctrl+K (clone, in place)
    • right-mouse button drag
  • finishing up
    • activate magnetic object snapping
    • order/stack the buttons to create your navbar
    • with text tool, modify each button text
      (note that since each button is soft-grouped, changing the text on either layer will change the text on the other layer)
    • change each button's Web Properties > Link (tab), as needed

If there are errors in the process, please bring them to my attention (and I will edit this post). Mercí.