K2 elements are not visible in Bottom positions

Hi,
I use News Show Pro GK5 module to display K2 category
when I set bottom positions for this module, I can only see the title of the module on the position. No category or element can be seen
I've tried Bottom, bottom1, bottom2, bottom3, mainbodybottom...
I can see the elements without any problem if I use "header" position only but this is not what I want
How can I displat the K2 category in the bottom position please ?
Thanks

It only works when I choose to add the 4 first categories in the list of Data Source
when I choose only one category or the first, 3rd and 4th in the list, it doesn't work anymore. I'm going maaaad !!

Has anyone an explanation ?
I really can't display K2 category at bottom positions.