Cre Loaded b2b 6.2 add to a cart error

Hi, i have a creloaded b2b 6.2 and i have this strange problem... it only happend with this one item... when i click add to a cart the item dont go to the cart, it show the cart empty.... but if click in cart it will show the item in cart.... now this just happen sometimes only because sometimes i click ad to a cart in this item and it goes to the cart... other than that the shopping cart has no problem. i need only advice.... escrow and payment after this its fix. budget 20 to 30 Thanks