In a VBA Sub, I issue this command:

Dim IsItOpen As Variant
IsItOpen = Application.Run("personal.xla!IsOpenWB", "chart of accounts.xlsx")

And the function in personal.xla is:
Public Function isopenwb(ByVal WBname As String) As Boolean
'returns true if workbook is open
Dim objWorkbook As Object
On Error Resume Next
isopenwb = False
Set objWorkbook = Workbooks(WBname)
If Err = 0 Then isopenwb = True
End Function

But I get an error, "The Macro 'personal.xla!IsOpenWB' cannot be found.
Ideas?