Subtotal incorrect since adding tax to shipping

I recently changed that there must be also TAX on my shippingcosts. Since then, my subtotal is incorrect.

For example here is my last invoice:

Product 8,36 (excl VAT)

Subtotal excl VAT: 7,73 (THIS IS WRONG, BUT WHY)
Standard shipping 3,95 (this is incl)(really would like this to be excl also.....)
VAT 19% 2,22 (this is correct, refering to my total below)
Total: 13,90 (also correct)

So, my subtotal excl VAT is incorrect and i would also see my shipping costs excl. if possible.

I really appreciate your help.
Thanks in advance:yes:

Well, i fixed it myself.

The problem was the subtotal was calculated by counting all productprices minus the tax of the shipping costs...