Not a valid add-in error message?
 

I posted yesterday about digital signatures and someone suggested that I
could also use an add-in as well, but I get the error message that my xla
file is not a valid add-in.

I'm new to add-ins and don't really understand how this will work (or if it
will even work for me!). To create the add-in, I first compiled my VBA
project and then saved it as a XLA file. I will be storing this WB on a
network shared folder, will the add-in automatically load my form for all
users, or will they have to install the add-in before it works? Will add-ins
even work with forms?

I am running Excel 2003 and have a workbook that contains four worksheets.
I have a form that I created (which contains 99% of my code) that will allow
for user input and searching of one of the worksheets. The only code that my
module contains is to load the form and my worksheet contains code to make
certain sheets visible.

Any help would be greatly appreciated - any links to good sites where I can
learn more would be great too!