SEF Problem on Checkout Link

-- url of the page with the problem -- : dev.compostwerks.com
-- HikaShop version -- : 2.6.0
-- Joomla version -- : 3.4.4
-- PHP version -- : 5.3
-- Browser(s) name and version -- : Internet Explorer 11
-- Error-message(debug-mod must be tuned on) -- : page doesn't display correctly because of incorrect paths.

Proceed to checkout button doesn't go to correct url when native SEF is enabled. It adds a second sef alias and then can't find the template css.

I enabled the System SEF Plugin and the problem is resolved!