1. Remove or comment out this line:
ActiveChart.SetSourceData Source:=DataRange, PlotBy:=xlColumns

Since you already have the chart  in place you don't need to redefine
and plot. Since DataRange is only one column wide you end up only
plotting one series, therefore later when you refer to series 2 and 3
etc. it balks. Just make sure you have 3 series and the chart type as
you like it before running the macro.

2. The line
Set TimeRange = Range("Sheet3!C7").Resize(amtrows, 1)
I believe should be:
Set TimeFrame = Range("Sheet3!C7").Resize(amtrows, 1)
since you have no Dim statement for TimeRange, but have one for
TimeFrame!

3. You've done the same as before with the three lines:
ActiveChart.SeriesCollection(1).XValues = Range(TimeFrame)
ActiveChart.SeriesCollection(2).XValues = Range(TimeFrame)
ActiveChart.SeriesCollection(3).XValues = Range(TimeFrame)

TimeFrame is already a range so amend to:
ActiveChart.SeriesCollection(1).XValues = TimeFrame
ActiveChart.SeriesCollection(2).XValues = TimeFrame
ActiveChart.SeriesCollection(3).XValues = TimeFrame