LotusScript Mystery

I'm a long-time user of 1-2-3 and have used Macros for years.  I've
just begun to try to learn LotusScript and very quickly ran into a
mystery involving "buttons" and subroutines.

I have an old Lotus 123 tutorial that shows how to set up a button on
a sheet that can be clicked to run a simple subroutine.  That involves
clicking on Create|Button, creating, placing (and naming) a button on
a sheet, and then invoking "IDE" to create a simple Button|Click
subroutine.  Creating the Button|Click subroutine supposedly involves
only the insertion of the name of the (separate, global) subroutine in
the Button|Click subroutine, as follows:

sub
   (name of subroutine to be run on click)
end sub

That works perfectly in the tutorial.  When I follow the exact same
procedure, step-by-step, for one of my own worksheets, I keep running
into the error message that the name of the (seperate, global) sub
that I insert in the Button|Click subroutine is not a subroutine or
function name.  I've tried this several times and checked carefully to
be sure that the Global subroutine whose name I use in the
Button|Click sub does indded exist, is listed among the Global script
subroutines, and has been stored with the worksheet.

Any LotusScript experts out there who can give me a clue as to why the
Button|Click sub won't work in my 1-2-3 file, yet does so beautifully
in the Lotus "Using Lotus 1-2-3" tutorial file?

The only basic difference between my workbook and the tutorial file is
that  my own 1-2-3 file has several sheets while the tutorial has only
one sheet.  Could my problem be related to that somehow?  Also -- if I
invoke a stored Macro in the Button|Click sub, using "[name of Macro]
.MacroRun," that works beautifully.  Why won't placing the name of the
equivalent Script in the Button|Click sub work?

Any and all suggestions of what to look for will be gratefully
received.

Thanks,
Joe