Passing form variables

I am trying to pass a variable from a cfgrid into an action page. The form looks like this.

<cfgrid name="data" query="movieList" height="200" onChange="submitForm()">
<cfgridcolumn name="movie_title" header="Movie Title" headeralign="left" dataalign="left">
</cfgrid>

my action page looks like this.

<cfsearch
collection="showmovies"
name="getMovies"
criteria="#form.movie_title#"
maxrows="100">

and then I ouput the results.

The error I am getting is

"Element MOVIE_TITLE is undefined in FORM"

I am not sure why I am getting that. I works fine in a regular HTML form.

Thanks,