I have a scatter chart with two data series plotting time and temperature curves - one for water temperature as it heats and the other for when it cools. My total time range runs from 11:46 to 13:59, and everything fits nicely on the graph as the X-axis is limited to that range. But when I add a new value '14:08' the x-axis resets itself to begin with 0:00 and my graph takes up only a narrow band of the graph space. I've tried changing the x-axis options from "auto" to "fixed" begining with 11:00 but it keeps resetting to 0.0. Any ideas how I can add additional time values and keep the graph limited to only my total time range?

Many thanks!