Hi,
You have a bootstrap popup problem with your template.
When you click on "add" or "edit" a popup is opend and because your template is not right compatible with the bootstrap popup, you don't see it.
But the popup is in the page, you can see a part in the bottom left of the page.
Please change the popup mode in your Hikashop configuration. By using the "mootools" popup you shouldn't have this kind of problem.
Regards,
Jerome - Obsidev.com
HikaMarket & HikaSerial developer / HikaShop core dev team.
Also helping the HikaShop support team when having some time or couldn't sleep.
By the way, do not send me private message, use the "contact us" form instead.