Prosper: high quality slides in LaTeX

I want to refer to equations on my slides by number.
E.g. I have an equation with a label:

\label{eq:tnn.def}

Later I refer to equation (\ref{eq:tnn.def}).

When I latex the file I get told that there are undefined
references; checking the log file indicates that
eq:tnn.def is undefined. And indeed there is no mention
of it in the .aux file.

It is not possible to use labels and references in the Prosper
style? Or is there something that needs to be done
that I am not doing.

cheers,

Rolf Turner
rolf@math.unb.ca