1.5.0 Coupon, table rate and sub-total recalculation issue.

[simpledomaining]

I have a table rate shipping set for spending up to $49.99 and free shipping for spending $50 and up.
I have a coupon for 1 product that is worth $25.95 and its set up for $25.95 discount (all other products are restricted, and we are trying to give this product for free basically).
Now the problem is if customer adds into the cart $50 worth items including the item eligible for this coupon, his orders total at checkout becomes $50, then he applies the coupon , it takes out - $25.95 and order total becomes $24.05, but free shipping rules still apply, because sub-total is not being recalculated. How can this get fixed? Because what happens is customer does not really spend $50 and he gets the free shipping option, and in this case he should not get it.

Sub-Total:$50.00
Discount Coupon: -$25.95 (coupon number)
(I think here should be one more line "Subtotal after discount" and table rate shipping (that is based on how much person spends) should be calculated from this amount)
Best Rate $0.00
TAX : $2.21
Total: $26.26


any advise would be appreciated.
i am using upgraded from 1.3.9h to 1.5.0 version of zen-cart.
in order total i have
Sub total 100
Discount Coupon 198
Shipping 200
Tax 300
Total 999