[O] Having problem with latex export of image file

[Robert Goldman]

I have the following in my org file:

#+CAPTION: Sample (partial) plan graph.
#+LABEL: fig:sampleGraph
#+ATTR_LaTeX: width=.9\textwidth
[[plan-with-tc-start.pdf]]

which I believe should give me a figure.  However, when I run this
through the latex export I get the following instead:

\hyperref[plan-with-tc-start.pdf]{plan-with-tc-start.pdf}

I pushed "pdf" onto image-file-name-extensions but that doesn't seem to
make any difference.

I figure there's something simple I'm doing wrong, but I can't figure
out what that is.

Thanks for any advice!

best,
r