Here is a bit nicer way to do it, as you don't have to repeat it in your four forms, add the code below as a public sub in a standard module:
Code:
Public Sub xlOpenExcel(iSheet as integer)
Dim xlApp As Object, i as Integer
Set xlApp = CreateObject("Excel.Application")
xlApp.Workbooks.Open ("\\musnas04\cpd_projects\CTO_OR\01- DOM COMMON\00- DOM- Common ORAC File (Access)\ORAC Parameters Details.xlsx")
For i=1 to 4
xlApp.ActiveWorkbook.Sheets(1).Visible = IIF(i=iSheet,True,False)
Next i
xlApp.Visible = True
DoCmd.Close acForm, "frm_waiting"
End Sub
'To use from your 4 forms
'Call xlOpenExcel(1) from form1, xlOpenExcel(2) from form2,etc.
Cheers,