We use Zencart and some modified Modules.
One of the modified Modules lets us validate the input which is entered by the customer.
Due to this validation the "Add to cart" function does not perform on Safari 5 and probably Chrome when this validation is active, however it works very well on FireFox
Want a experienced Zencart programmer to look into this , suggest and implement steps to rectify this.
Any other validation causing this browser issue should also be solved.
The changes should be emailed to us by the programmer.