warning

What does this warning Message mean? (Homepage)
<b>Warning</b>: Illegal string offset ‘tour_phys’ in <b>/www/htdocs/w0170ca2/dev-horizonttours.pro4web.net/wp-content/plugins/travel-booking/inc/widgets.php</b> on line <b>43</b><br />
<option value=”zugreisen”>Zugreisen</option> </select>
</div>
<div class=”form-field-select”><select name=”tourtax[pa_destination]”><option value=”0″>destination</option><br />
<b>Warning</b>: Illegal string offset ‘pa_destination’ in <b>/www/htdocs/w0170ca2/dev-horizonttours.pro4web.net/wp-content/plugins/travel-booking/inc/widgets.php</b> on line <b>63</b><br />

as product attributes do not work, I added some like countries, Tour Type but they do not show up
also the booking form is not available

please advice
Thank you