Open Excel from PowerPoint

Hi,
I'm having trouble opening a particular worksheet from PowerPoint. I can open the Workbook fine, but I can't open a particular worksheet that I want. Can anyone help?
Dim tempname, pptname, refbox As String

tempname = ActivePresentation.name
i = Strings.Len(tempname)
pptname = Strings.Left(tempname, i - 4)


Set xlsApp = CreateObject("Excel.Application")
xlsApp.Visible = True
Dim path As String

path = "S:\SHARE\drf\Automation\Index\Indexsheet.xls"

Set newxls = xlsApp.Workbooks.Open(path)
Worksheets(pptname).Activate

Thank you!