image load problem and gk3 photoslide

hello, a few hours ago when i choose an image to insert to an article through backend it cant be done, if i do it through frontend (submit an article as a user its ok)

also when i go to add a new slide in gk3 photoslide i press the button but the box to choose the group doesnt appear.

my template is hewahoo, paokizein.gr/paokizen
and administrator is paokizein.gr/paokizen/administrator

Hi

There is no site under this address. Please give me a propper one. Are You sure the installation process went fine ? Did You set all permissions right on files/folders ?