ÖÅÄ in capital letters disappers with theme Futura

Hi

I use Opencart for a Swedish webshop where I use Swedish characters. I installed Futura theme, which uses capital letters in some headings However ÅÄÖ in capital letters disappears. It works well with åäö in lower letters but when converted to capital letters they disappears.
For example in file shop/catalog/language/theme/swedish.php
$_['button_go'] = 'Sök';
is shown as SK in the browser

Any ideas?

Thanks for your help
gemini

I also have the same problem with another theme.
Anyone know how to solve it?