Custom Post Types not all in dropdown

I use a GF form to add entries to a custom post type ‘trainingen’.

Then I want to add a drill to this training with another GF form. In that form I have a dropdown field which I want to populate with the ‘trainingen’ I already added. So I check populate with a post type (trainingen).

My problem is that it does not show any trainingen I added with the GF form although there are (published). When I add a trainingen without the form, so through admin, the trainingen shows up in my dropdown. I do not see any differences between all posts.

Hope someone can help.

http://wordpress.org/plugins/gravity-forms-custom-post-types/