[Wiki Loves Monuments] Difference between statistic and category

[Karl Gruber]

How I can find out the difference from statistic in 
http://toolserver.org/~emijrp/wlm/stats.php and the Category:Images from 
Wiki Loves Monuments 2012 in Slovakia. Everytime is the statistic with 
one image lower then the category. I know there are only 600 images in. 
But beginning from 100 photos it appears. Perhaps somebody can help me 
to find out the discrepance. It's not the time lag, it appears also with 
an 1 day, if nothing was uploaded.

regards
Karl