shipping zone rates

Zen Cart 1.3.8a

I'm using the zone rates module based on weight and just had an email from a customer regarding the shipping.

he ordered 2 items where the attributes are showing -0.1 on the weight, that he ordered.
The weight showing on the checkout page is 0.18kg

the UK is on the shippingzone 2
theres no taxclass for that
countries are
AT,BE,HR,CY,CZ,DK,FI,FR,DE,GI,GR,IE,IT,LI,LU,MK,MT,MC,NL,NO,PL,PT,SK,SE,CH,TR,GB,YU

shippingtable is

0.5:12,1:20,2:23,3:26,4:29,5:32,6:35,7:38,8:41,9:44,10:47,11:50,12:53,13:56,14:59,15:62,16:65,17:68,18:71,19:74,20:77,25:85,30:100

handling is 5

But he gets a total of 34€ shippingcosts, how is that possible, what am I doing wrong.
But according to my settings it should be 12shipping + 5 handling =17

Thanks

Check your currency settings. Make sure that whatever currency you have chosen as your DEFAULT currency, as a value of 1.0000000.

Then UPDATE CURRENCIES

Also, check your shipping TARE settings (the values that add "extra" to shipping weights to account for weight in the packaging)

admin ... configuration ... shipping/packaging

It was the tare settings, works perfect now, thanks for the quick help