Custom Field ordering can not be executed?

Klicikt on header order buttom and its worked!

Today I updated EventBooking from 1.6.3 to 1.6.5 and now it shows in the backend the ordering of all fields (predefined and custom fields) - so far I am happy!
But the Up/down errors for changing the ordering do not work! Do you have any ideas what could be the reason?

Br Gerd
For Joomla 3.3

Click on the column heading then the arrows work.....

That's correct. Thanks Andrew for helping me answer this question. FYT, it is mentioned in documentation at documentation.joomdonation.com/2-events-...ing-of-custom-fields

Regards,

Tuan