I don't tend to use GetObject when working with Excel via VBA, maybe that's the issue.
Your excelworksheet variable is actually pointing to a "workbook" I believe, this isn't an issue, just a naming issue.
' get Excel
Set objXLApp = CreateObject("Excel.Application")
' add workbook
Set ExcelWorksheet = objXLApp.ActiveWorkbook
' write sample data to sheet
For i = 1 To 10
ExcelWorksheet.worksheets(1).cells(i, 1) = 3 * i
' check data to ensure it's been written
For i = 10 To 1 Step -1
j = ExcelWorksheet.worksheets(1).cells(i, 1).Value
' tidy up
Set ExcelWorksheet = Nothing