tbl, beginner's difficulty with 'box'

[wa371]

When I give a 'box' directive in the tbl input, it prints the vertical
lines of the box one at a time, at the BOTTOM of the page, AFTER it
has printed everything else.
I tried the examples given by McGilton and Morgan on page 405ff
and had no better luck.
What I am doing wrong?

Bernd <bear-nd>
UUCP: ...!ucbvax!sdcsvax!sdcc12!wa371,   ARPA: sdcsvax!sdcc12!wa371 at nosc
            *** hooray for USENET ***