Megamenu in second language

Our website has two store views(Greek-English).
Categories have different url for each language. 
If go to “JoomlArt >JM Mega Menu > Manage Menu Groups > Item manager for Greek” and select a Greek category then link auto generated in English language.(That why we used url rewrite) If we select custom-link and complete link with category url in Greek then in front-end url is correct but “page not found error” displayed.
In English view menu works fine.
If we disable Mega Menu from admin panel then menu works fine for both languages with correct urls.  
http://demo.softwebpages.gr/charachatzina
 
if you click the last menu item in greek “ΕΚΠΤΩΣΕΙΣ” then it returns 404.
If we disable megamenu, and click the same menu item it warks fine.
 
Thanks in advance,