Attempting to change source data in Excel of a chart in PowerPoint

Hi y'all. I'm trying to manipulate a chart in PowerPoint that has source data in Excel. To start off, the chart is a simple Hi-Low-Close stock chart that has six categories along the X axis. What I want to do is be able to edit the chart to give it an additional five categories along the X axis for a total of 11. Here's the relevant part of the code I've got now. The chart named "Chart7" on slide 2 of the PowerPoint presentation is the one I want to change. What I want to do is be able to press a button in PowerPoint named "1" and the chart will add in 5 more categories (This Quarter 1, This Half Year 1, etc) along the X axis. It's okay that they'd have no values right now.

I know there's some redundancy with the first six lines of the ChartManip sub, but if I don't have that there, nothing changes when I press the button. When I do have it there like shown in the code below, nothing happens the first time I press it. The second time I press it though, it edits the data in Excel, but it only makes the chart data H36:K45 instead of H36:K46 like it says it should, so I think that's the line that's not working. I'll mark that in the code in red. I think the reason that it's only going through K45 is because the way I'm adding in the new categories in the X axis, I want them in between the ones that already exist. So it's automatically adjusting the source data already except that it's not capturing the new "Three Years 1" category I'm adding at the very end. The part with all the cutting is just adjusting the cells in Excel, so I don't think there should be a problem there. Eventually, I'll put in a shape named "2" that you can press to undo the new X axis categories, but I think I can figure that out once I know how to put them there in the first place. Any help would be greatly appreciated!

Sub Test(oshp As Shape)

Dim myChart As Chart
Dim myChartData As ChartData
Dim gWorkBook As Excel.Workbook
Dim gWorkSheet As Excel.Worksheet

Set myChart = ActivePresentation.Slides(2).Shapes("Chart7").Chart
Set myChartData = myChart.ChartData
myChartData.Activate
Set gWorkBook = myChart.ChartData.Workbook
Set gWorkSheet = gWorkBook.Worksheets(1)
gWorkSheet.Application.ScreenUpdating = False

If oshp.Name = "1" Then
ChartManip
End If

If oshp.Name = "2" Then
EndChartManip
End If

gWorkBook.Save
gWorkBook.Close
myChartData.Activate
Set gWorkSheet = Nothing
Set gWorkBook = Nothing
Set myChartData = Nothing
Set myChart = Nothing
ActivePresentation.Application.Activate
ActivePresentation.SlideShowSettings.Run

End Sub

Public Sub ChartManip()

Set myChart = ActivePresentation.Slides(2).Shapes("Chart7").Chart
Set myChartData = myChart.ChartData
myChartData.Activate
Set gWorkBook = myChart.ChartData.Workbook
Set gWorkSheet = gWorkBook.Worksheets(1)
gWorkSheet.Application.ScreenUpdating = False
gWorkSheet.Range("H38:K41").Select
Selection.Cut Destination:=gWorkSheet.Range("H39:K42")
gWorkSheet.Range("H40:K42").Select
Selection.Cut Destination:=gWorkSheet.Range("H41:K43")
gWorkSheet.Range("H42:K43").Select
Selection.Cut Destination:=gWorkSheet.Range("H43:K44")
gWorkSheet.Range("H44:K44").Select
Selection.Cut Destination:=gWorkSheet.Range("H45:K45")
gWorkSheet.Range("H38").Select
ActiveCell.FormulaR1C1 = "This Quarter 1"
gWorkSheet.Range("H40").Select
ActiveCell.FormulaR1C1 = "This Half Year 1"
gWorkSheet.Range("H42").Select
ActiveCell.FormulaR1C1 = "This Year 1"
gWorkSheet.Range("H44").Select
ActiveCell.FormulaR1C1 = "Two Years 1"
gWorkSheet.Range("H46").Select
ActiveCell.FormulaR1C1 = "Three Years 1"
myChart.SetSourceData Source:=gWorkSheet.Range("H36:K46")

End Sub

Edit: I think the line in red is doing something actually, but no matter what, it never goes past H36:K45.