Scroll Bar (Slider) Problem

[Wadzy97]

Hey everyone, I need to make my scroll bar move by 0.1 each time the arrows are clicked (I believe this is the 'small change' option) but when I go to enter it in it comes up with an error message saying "Invalid property Value". Also I've set the minimum to be -1 and the maximum to be 2 however when I scroll to where it should say -1 it has 65535 instead? Any ideas on what I can do?

Thanks in advance!