Add product in shopping card with Appointment

I have installed Appointments, market press and I'm trying to make them work together.

I have a problem with the add to card.
I see that every time I generate a purchase,the system creates a product variant on backend.
Every time I add an appointment to shopping card automatically creates a new variant.

My problem is that on occasion the add card loses index of the product and show it to me as follows:

Appointment: 0

And when I'm loading products sum the quantity of the same product.

The correct way would be:

Appointment: 24 (May 31, 2013 11:30 a.m.)

********Removed Site data for security reasons*******

Please I need help, if I configured something incorrectly you can tell me

Thank you