Appointments+ Nothing happens when selecting a date


So the appointment plugin does not work fully, calendar shows but nothing happens when selecting an available date or time..

I read the related section in the FAQ and a previous topic:

but i could not get any further... I know the problem is with my theme becaus with the default WP theme it works. I looked at the js warnings.
My theme has nothing special except maybe a fullscreen image slider in the back that works with maximage (uses some jQuery and ajax i think). I tried disabling it and this removed the last warning
"Expected ':' but found 'undefined'. Declaration dropped.
Line: 0"
but the plugin still does not work...

Any recommendation on what to do, where to look? start?