Thanks monica for sending me in the right direction, but it turned out to be a spelling mistake.
pawtucket/themes/default/views/Search/ca_objects_advanced_search_objects_html.php
line 35:
{{{ca_objects.dates.dates_value%width=200px&height=40px&useDatePicker=0}}}
should be
{{{ca_objects.date.dates_value%width=200px&height=40px&useDatePicker=0}}}
when I made this correction the function started working correctly