The trick is that I'm trying to inline a variable to the template to send in variable table rows.
Not sure if this is what you need, but here's my OptionalTableRow template:
{{ #if: {{{2|}}} | {{!}} '''{{{1}}}''': {{!}}{{!}} {{{2}}} {{!}}- }}<noinclude> == Usage ==
<pre> {{OptionalTableRow|designation|value}} </pre> [[Category:Templates]] </noinclude>
You will need the "pipe template"; the need for this is described at Meta: http://meta.wikimedia.org/wiki/Template:%21 In fact, this might be the reason why your approach didn't work... !?
-- F.