Can't change table rate amount for shipping

[Pompidompie]

I can't get it to work
If i get it to work on the % then i can't get it to work on the € and the other way around.

If i set the ot_coupon to include tax false, re-calculate tax to standard and tax class high (we also have low and free), and use 10% discount coupon, it works.

Subtotaal 19.95
coupon -1.99
shipping 1.50
tax 3.37
totaal 19.46

But if I change the coupon to amount, € 10,-
It shows this
subtotal 19.95
coupon -11.74
shipping 1.50
tax 1.98
total 9.71

That is not right at all
No matter what I change, it's either the % that works, or the €, but never both.

[Pompidompie]

Still havend figured it out. Does somebody have an idea of what the problem could be?