Attachments don't display

[Jarek]

After addition attachments to post, they doesn't display. Instead of this, appears
an empty quadrat. It is not a matter of style, because a issue occures both on 

default and flatty 2.0 style. Anyone knows a solution?

Thanx in advance for help

Forum: http://dyskusjebiblijne.info.pl/index.php

Test account:
Tester
test12