Can somebody please help me!

I wish to use the function 'WORKDAY' in a VBA routine available from the
Analysis Tool-pak Add-Ins.
I have ticked off the Analysis Toolpak and Analysis Toolpak - VBA
I have used it successfully in a cell so I am sure the format is correct.
E.G. =IF(L3 < "",WORKDAY(L3,AA3,Holiday_List),"")
The result is a date advanced by the value in cell AA3 excluding weekends
and public holidays.
Cell L3 has a date and cell AA3 has an integer number while 'Holiday_List'
has a range of dates.

Below is the code on a form where 'TBoxSDate' is a date and 'TboxDaysPt' is
an integer number.
This is the line:
lblPayDte = Application.WorksheetFunction.WORKDAY(TBoxSDate,
TboxDaysPt,Holiday_List)

When coding the function 'WORKDAY' is not listed after WorksheetFunction so
I realise that it is not available. Why?

When running the form and invoking the line above, it says 'Object Required'

Are Add-in functions noy available within a form?

Peter Bircher