Erratic eCart Update(s)

Thanks Jason for help!

Still- As I hit 'Add to Cart' the (first time) in item_Details.php, it does not add to quick cart.

If I go to the quick cart on index.php, it updates first time, on first click, from the page, item_Details.php.

Again, if I 'reload' item_Details.php in browser, quick cart will update. (By Qty. 1)
If I go to index.php (to check quantity update from previous page I was on, item_Details.php) and then go back to that page [item_Details.php], it then updates first 'Add to Cart' that did not work while on the page [items_Details.php] the first time. (Same as a reload, I guess.)

Also, anytime I get the drop down alert to 'Send Form' in Browser, it Auto- Updates Quick Cart Quantity by 1. (I get this alert as I ping- pong between index.php and item_Details.php.)

Lastly, I made a cart.php page to come up as I press the 'View' button on quick cart, index.php, no cart.php page comes up. Nothing comes up.

I assume I have to build a cart.php or cart_Details.php page from scratch, as I did not see it in the eCart Sample Store Original Files that I am obviously working off of. Either way, I built a dummy page (cart.php) with text, nothing comes up.