wxgraphs rain gagues error

https://weather.scottsworld.info/wxgraphs/wxgraphs_IIStest.html I finally got WXgraphs working again under php 7.3 (bluehost my new server only offers 7.0 - 7.3) and jpgraph-4.2.9 (latest version I downloaded. But

Rain gauges all say illegal error

JpGraph Error: 25068 A plot has an illegal scale. This could for example be that you are trying to used text auto scaling to draw a line plot with only one point or that the plot area is too small. It could also be that that no input data Value is numeric (perhaps only "-" or "X")