Email after submit and checkbox

[SebasJ]

I have a form wich contains a checkbox. After form submission the data is saved in a database, and send by email, with an attachments.

All seems well, for one thing:

The checkbox selection is correct in the database, and also in de attachment (PDF)
But in the emailbody it is incorrect, there is always only one item in the mail body.
Even if there are 2 or 3 items selected.

Has any one a suggestion to why,?

Joomla: 3.3.0
Fabrik: 3.1.1

Thanks in advance

SebasJ