Homebrew PCBs

I entered 3% h2o2 and 15% hcl into the calculator. The result is:

Mix h2o2: 66.7%; hcl: 53.3%; water: -20%

What does it mean if I get a water result of minus 20% ?

Thanks,
Dave

-=-=-=-

>Here's a web page about using the acid/peroxide etchant. About half 
>way down the page is a calculator for the mix. Input your % acid and 
>% peroxide and it tells you how much water you have to add.
>
>http://www.dr-lex.be/hardware/tonertransfer.html