Kunena Forum 3.0.6: Unable to Sort Categories - Joomla! Forum - community, help and support

using: kunena 3.0.6 & joomla 3.3.6

in kunena > category manager, when trying re-order categories, tab handle greyed out mouse-over message "please sort order enable reordering".

however, in 'sort table by', there no label called 'order' sort by. closest label (logically) designation 'reorder' selecting option nothing, nor re-enable category row handles (the 3 stacked dots left of category name) use reorder rows in such table.

any idea how sort categories?

i've tried sorting according other criteria sorting 'reorder' no avail.

to illustrate, imagine have 3 kunena forum categories displayed in front-end follows:

bananas
cherries
apples

and want re-order (in back-end > components > kunena forum > category manager) categories as:

apples
bananas
cherries

there easy drag'n'drop interface , there shouldn't problem changing ordering. i've checked out on testing polygon , fine (if understood question correct).
but suppose may have script conflict in back-end due 3rd party extensions.
have got other 3rd party extensions installed except kunena 3.0.6?

you may check out issues via webug add-on chrome or firebug firefox , click on "console" tab verify possible script issues.