Function bWkOpen(sTargetWkName) As Boolean
Dim xlWk As Workbook
On Error Resume Next
Err.Clear
Set xlWk = Workbooks(sTargetWkName)
If Err.Number = 0 Then
bWkOpen = True
Else
bWkOpen = False
Err.Clear
End If
Set xlWk = Nothing
End Function
Sub test()
MsgBox bWkOpen("Book1.xls")
End Sub