restore theme version

hi, I'd like to restore a previous version, but I keep getting this:

Maintenance

Your website will be back online soon,
please retry in a few minutes.
500

please can you give a link to your forum ?

Hello

Could you please provide information:
- Where do you try to restore your theme (admin panel or founder's tool)
- What is the date you select?
- The url of the forum with the problem:

http://ex-iskon.forumcroatian.com/

hi, yes that is my forum.

I try it over the admin panel > display > skins > themes management > restore the skin

when I chose the one before 2 days, it hits me with the "maintenance error"

could you please try and use the Forums utilities this should backup your forum to the old skin without any problems.