Setting prize with tax wont save

[Roman Hána]

Hi guys, I am starting to use presta, have one question about adding product.

 

When I add some product and go to fill in the price, I have two options - to enter price without tax and wit tax.

 

When I add price with tax and hit save, nothing will be saved. I have to recount the price to be without tax and fill it in, than I save all OK.

The weird thing is that if I want to use the field with tax first to see the price without tax (presta will recalculate), delete and fill the price into the field without tax, I cant save either.

 

Thats normal or buggy?

Here is pic of what I mean:

http://screencast.com/t/v9vktWPAwGUO

 

I am using 1.6.1.7 version with default template.

 

Thanks for any advice