"Add to cart" problem: "Your Shopping Cart Is Empty"

[weber]

I know that there are several threads on it. but none of them help.

when i click the add to cart button on product_info page, some times it can be added, but sometime not. i success for 6-7 times and then fail 1-2 times. looks it happens randomly. anybody to tell me how to debug?

STORE_SESSION set to 'db'
configure.php shall not have problem i check many times.

a lot plugins but i can't remove them. so any one tell me how to debug? why the cart see nothing add? main_cart_action.php?

[weber]

for more detail, sometimes
there are some 4 items in cart. i click add to cart and redirect to the cart there are still 4 items. if i return to the previous page(back button on browser) and then click the add to cart once or twice then it works...

any idea?

[weber]

any help? anyone can tell me how to find out where and what is wrong?