How do I close an Excel Workbook instance to prevent sharing violation?

Here's an excerpt of my code:

Dim xlApp As Excel.Application ' new instantiation of Excel
Dim xlBook As Excel.Workbook
Dim xlSheet As Excel.Worksheet

'-- Open Excel and Select CheckBook Worksheet
xlApp.Workbooks.Open excelFile
xlApp.ActiveWorkbook.Worksheets
(txtActiveWorkSheet.Text).Select

'-- Code in here to Update Excel Workbook


xlApp.ActiveWorkbook.Save
xlApp.ActiveWorkbook.Close
xlApp.Workbooks.Close

Set xlSheet = Nothing
Set xlBook = Nothing
Set xlApp = Nothing

Have you tried

xlBook.close

or
'*** Close and save the workbook ***
xlBook.Close(vbYes)

I thought I had tried that, but I'm not sure anymore. I will give it a try. Thank you krinpit