modal popup doesn't work for registered users

[zagrox]

Hello guys, I'm using VM 2.0.12 and Joomla 2.5. My shop works fine except when a registered user is clicking on addtocart.
modal popup doesn't show but the product is adding to card silently. its working fine when you're adding a product as a guest.
I don't want to disable the modal popup from configuration. is there any solution that you can show me?

[bytelord]

Hello,

I could say js conflict .. is there any extension that comes up when a registered user logons uses javascript?

Regards