problem in product list

[blackrain02]

hello

in list of my products which is over 20 product and show in 2 page my problem in here that some of  products of page 1 show in page 2 and some of product show in no pages

why this problem happen?
how can i solve it?

sorry for my bad English
thanks

[jenkinhill]

See http://forum.virtuemart.net/index.php?topic=128401.0

[blackrain02]

virtuemart version: 3.0.10
joomla version: 3.4.8
php version: 5.5.28

my site: http://www.uhlsportfootball.com/fa/perspolis.html

user:test
pass:test