I have a User Defined Function in an add-in (XLA file created by myself).
What do I need to do in order to allow me to access it from code in another
project?

i.e.

The function is a Public Function located in the .xla file and is called
GetFolderName. I use it as follows:-

FolderName = GetFolderName("Title for GetFolderName")

But I get the error:-
"Sub or Function not defined"

What do I need to change in order to access a UDF stored in an XLA from a
seperate excel workbook?

Ta

Andy