I am using an Excel Add-in for an Erlangs: http://abstractmicro.com/erlang/helppages/ref-erlbblockage.htm
I try to call the Erlang-B function within the Add-in from within VBA thus:
Function Erl(Erlangs As Double, Capacity As Double)
Erl = Application.WorksheetFunction.ErlbBlockage(Capacity, Erlangs)
End Function
...but it doesn't work. I get #VALUE! returned in the Excel cell. I think it is because the function is not part of standard Excel (it is in the Add-in). So how do I call it?