Maybe the following example will help.
This code is designed to backup the "Backend" database. It will not backup the file that you have currently open.
The trick to remember is that this code must be triggered from an "Unbound Form", with no other bound forms open or you will receive a "File in use" error (error 70).
You only need to change the value for "strSource" and "strDest" for this code to work.
' *********************** Start Code *********************
Public Sub BackUp()
On Error GoTo Err_Backup
Dim strSource As String, strDest As String, strError As String
Dim strMsgComplete As String, strTitleComplete As String
strMsgComplete = "The Database was Sucessfully Saved to Diskette." _
& vbCrLf & vbCrLf & "Remove Disk from Drive and Place in Safe Location."
strTitleComplete = " Backup Complete"
BeginBackup:
DoCmd.Hourglass True
' Path to where backend database is located
strSource = "C:\Emp_DB\091_be.mdb"
' Destination to where data file is to be copied
strDest = "A:\091_be.mdb"
FileCopy strSource, strDest
'Backup has completed
DoCmd.Hourglass False
MsgBox strMsgComplete, vbInformation + vbOKOnly, strTitleComplete
Exit_Backup:
Exit Sub
Err_Backup:
Select Case Err.Number
Case 61
strError = "The Floppy Disk is full, Cannot Save to this Disk." _
& vbCrLf & vbCrLf & "Insert a New Disk then Click ""OK"""
If MsgBox(strError, vbCritical + vbOKCancel, " Disk Full"

= vbCancel Then
DoCmd.Hourglass False
DoCmd.SetWarnings False
Resume Exit_Backup
Else
Resume BeginBackup
End If
Case 70
strError = "The File is currently open." & vbCrLf & _
"The File can not be Backed Up at this time."
MsgBox strError, vbCritical, " File Open"
DoCmd.Hourglass False
DoCmd.SetWarnings False
Resume Exit_Backup
Case 71
strError = "There Is No Disk in Drive" & vbCrLf & vbCrLf & _
"Please Insert Disk then Click ""OK"""
If MsgBox(strError, vbCritical + vbOKCancel, " No Disk"

= vbCancel Then
DoCmd.Hourglass False
DoCmd.SetWarnings False
Resume Exit_Backup
Else
Resume BeginBackup
End If
Case Else
Err.Raise Err.Number, Err.Description
Resume Next
End Select
DoCmd.Hourglass False
Resume Exit_Backup
End Sub
' *********************** End Code *********************
HTH
RDH Ricky Hicks