Select data concurrant for chart

[always_confused]

Hello,

I am trying to plot a bunch of time series via a macro I've written. When the column of data are NOT concurrent (like Range("A:A") and Range("C:C")), it works fine. However if I want to plot Range B s Range A (timestamps in A, data in B), then the graph comes out all messed up (all condensed like it's not using the timestamp data at all), and when I select the graph to see what ranges it's using, the timestamp range is not selected. Has anyone encountered this issue or maybe know how to solve this? Here's the sub:

Sub make_plot(name As String, place As Range, data_col As Range, time_col As Range)
'plots data from sheet(name) in range place using data_col and time_col as source 

Application.ScreenUpdating = False

Dim chartObj_1 As ChartObject
Dim newChart As Chart
Dim lastrow As Long
lastrow = Sheets(name).Range("A" & Rows.Count).End(xlUp).Row
Set chartObj_1 = Sheets(name).ChartObjects.Add _
    (Left:=place.Left, Width:=place.Width, Top:=place.Top, Height:=place.Height)
Set newChart = chartObj_1.Chart

With newChart
    .HasTitle = True
    .ChartTitle.Text = data_col.Range("A1").Value
    .ChartType = xlXYScatter
    .HasLegend = False
    .SetSourceData Source:=Application.Union(time_col, data_col)
    .Axes(xlCategory).HasTitle = True
    .Axes(xlCategory).HasMajorGridlines = True
    .Axes(xlCategory).AxisTitle.Caption = "Time"
    .Axes(xlValue).TickLabels.NumberFormat = "0.000"
    .Axes(xlValue).MinimumScale = 8.4
    .Axes(xlValue).MaximumScale = 9
    With .SeriesCollection(1)
        .MarkerStyle = xlMarkerStyleCircle
        .MarkerSize = 2
    End With
End With
ActiveWorkbook.Save
Application.ScreenUpdating = True
End Sub

Here's how I' calling it

lastrow = Sheets("MySheet").Range("A" & Rows.Count).End(xlUp).Row

Call make_plot("MySheet", Range("K2:S18"), _   'this one doesn't work correctly
Range("B1:B" & lastrow), Range("A1:A" & lastrow))

Call make_plot("MySheet", Range("K21:S37"), _  'but this one works fine
Range("C1:C" & lastrow), Range("A1:A" & lastrow))