I've used the below before...

...the main part for checking/unchecking is to use the .installed.

Function Load_XL_AddIn(strFilePath As String, strAddInName As String)
As Boolean
Dim addXL As Excel.addin

On Error Resume Next
strAddInName = Left(strAddInName, Len(strAddInName) - 4)

Set addXL = Excel.AddIns(strAddInName)
If Err < 0 Then
Err.Clear

Set addXL = Excel.AddIns.Add(strFilePath, 1)
If Err < 0 Then
Load_XL_AddIn = False
GoTo Load_XL_AddIn_End
End If

End If

If Not addXL.Installed Then addXL.Installed = True
Load_XL_AddIn = True

Load_XL_AddIn_End:
Exit Function
End Function


--
MattShoreson
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