Thanks Dave, for clarifying this!
@Matthew:
XOWiki as authoring environment comes with many tastes and smells of authoring instruments. These instruments group, rougly, into "content model items" (::xowiki::Page, ::xowiki::Form, ...) and "presentation model items", i.e. basically authoring support in the richtext editor environment (block markers of all kinds: [[...]], {{...}}, >>...<<). While these concepts are of course interwoven, you were confusing them in the above attempt to create a form.
You were using a layout-only block marker (>>...<<) and tcl script blocks. The reason why it turned out blank is the character block between the >>,<< delimiter is resolved against CSS classes which allow some in-place layouting.
Generally speaking, it is not allowed to execute entire Tcl/XOTcl code blocks from within ::xowiki::Page content (richtext content). End-user or author-driven programming is only allowed in certain contexts and always mediated through a dedicated interface (includelets, for instance).
