This required sort behavior has been removed in Logger Pro 3.5 and newer; to avoid sorting, upgrade to version 3.5 or newer.

In Logger Pro 3.4.6, when plotting the data from one sensor versus the data from another sensor, or if the events with entry points were not entered in ascending order, AND a selection of a portion of the graph is made, Logger Pro can have problems performing the curve fit.

In version 3.4.5 and earlier, Logger Pro would silently use a subset of the selected points, and so the fit would sometimes be unexpectedly poor, or the fit might fail with a message that more points need to be selected.

In version 3.4.6, if the points on a graph are not sorted, any curve fit request will yield only a message to sort the data. On sorting the horizontal axis data, the fit will succeed, and the fit will use all the selected points.

To sort the data, do the following:
1. From the Data menu, choose Sort Data Set –> (data set name)
2. In the resulting dialog, choose the column graphed on the horizontal axis
3. Select either ascending or descending, and click OK.

Note that if your data table is sparse, with blank cells due to differing data collection rates on difference sensors, the sort may fail to allow a curve fit.

Or, if your horizontal-axis column is calculated, the sort will not be allowed.

In these cases, the workaround is to create a new Data Set with two manual columns. Copy and paste your two columns into this new data set. Sort on the horizontal axis column in the new Data Set; the sort will now succeed, and your curve fit will work. Upgrading to Logger Pro 3.5 or newer will avoid the sorting.